github.com/javascript-obfuscator/javascript-obfuscator
Advanced tools
JavaScript Obfuscator has reached over 1 million npm downloads per week. I am currently preparing an EB-1 immigration case and collecting independent evidence of the project’s real-world professional usage and impact.
If you use JavaScript Obfuscator in a company project — especially at a well-known company, large organization, or widely used product — I would be very grateful if you could contact me.
Helpful evidence may include a brief confirmation or, ideally, a 1–2 page reference letter describing:
I can provide a simple draft/template to make this easy.
Please contact me at: referenceletter@obfuscator.io
Thank you for supporting the project.
Obfuscator.io adds VM-based bytecode obfuscation to this package - your JavaScript functions are compiled to custom bytecode that runs on an embedded virtual machine. Each build produces unique opcodes and VM structure, making reverse engineering and automated deobfuscation dramatically harder.
| Protection goal | Free (this package) | obfuscator.io |
|---|---|---|
| Rename identifiers | ✅ variable/function renaming | ✅ + VM-local symbols never exposed as JavaScript |
| Obscure strings | ✅ string array + base64/rc4 | ✅ + strings embedded in bytecode constants |
| Obscure control flow | ✅ control flow flattening | ✅ full bytecode virtualization, vmJumpsEncoding (runtime-computed jump targets), vmDeadCodeInjection (fake bytecode sequences) |
| Resist decompilation | ⚠️ output is still JavaScript | ✅ custom opcodes, vmStatefulOpcodes (position-dependent opcode mapping), vmMacroOps (fused instructions), vmDecoyOpcodes (fake opcode handlers) |
| Resist automated LLM-based analysis | ❌ fully vulnerable (no LLM-specific defenses) | ✅ bytecode encryption + anti-LLM defenses in vmSelfDefending and vmDebugProtection |
| Encryption | ✅ stringArrayEncoding (base64/rc4 on extracted strings) | ✅ vmBytecodeEncoding (per-instruction encoding), vmBytecodeArrayEncoding (whole bytecode array as single block) |
| Anti-debugging | ✅ debugProtection (freezes browser DevTools) | ✅ vmDebugProtection (multi-layered anti-debugging and anti-analysis defenses) |
| Tamper detection | ✅ selfDefending (breaks if beautified) | ✅ vmSelfDefending (multi-layered tamper detection, anti-hooking, anti-reverse-engineering protection) |
| Runs offline, no network | ✅ | ❌ uses obfuscator.io API (requires token) |
Visit Obfuscator.io · Pro API methods
This package provides access to Obfuscator.io API via CLI and Node.js API.
JavaScript Obfuscator is a powerful free obfuscator for JavaScript, containing a variety of features which provide protection for your source code.
Key features:
The example of obfuscated code: github.com
It is not recommended to obfuscate vendor scripts and polyfills, since the obfuscated code is 15-80% slower (depends on options) and the files are significantly larger.
Install the package with Yarn or NPM and add it to your dependencies or devDependencies:
$ yarn add --dev javascript-obfuscator
or
$ npm install --save-dev javascript-obfuscator
From CDN:
<script src="https://cdn.jsdelivr.net/npm/javascript-obfuscator/dist/index.browser.js"></script>
From node_modules:
<script src="./node_modules/javascript-obfuscator/dist/index.browser.js"></script>
var JavaScriptObfuscator = require('javascript-obfuscator');
var obfuscationResult = JavaScriptObfuscator.obfuscate(
`
(function(){
var variable1 = '5' - 3;
var variable2 = '5' + 3;
var variable3 = '5' + - '2';
var variable4 = ['10','10','10','10','10'].map(parseInt);
var variable5 = 'foo ' + 1 + 1;
console.log(variable1);
console.log(variable2);
console.log(variable3);
console.log(variable4);
console.log(variable5);
})();
`,
{
compact: false,
controlFlowFlattening: true,
controlFlowFlatteningThreshold: 1,
numbersToExpressions: true,
simplify: true,
stringArrayShuffle: true,
splitStrings: true,
stringArrayThreshold: 1
}
);
console.log(obfuscationResult.getObfuscatedCode());
/*
var _0x9947 = [
'map',
'log',
'foo\x20',
'bvmqO',
'133039ViRMWR',
'xPfLC',
'ytpdx',
'1243717qSZCyh',
'2|7|4|6|9|',
'1ErtbCr',
'1608314VKvthn',
'1ZRaFKN',
'XBoAA',
'423266kQOYHV',
'3|0|5|8|1',
'235064xPNdKe',
'13RUDZfG',
'157gNPQGm',
'1639212MvnHZL',
'rDjOa',
'iBHph',
'9926iRHoRl',
'split'
];
function _0x33e4(_0x1809b5, _0x37ef6e) {
return _0x33e4 = function (_0x338a69, _0x39ad79) {
_0x338a69 = _0x338a69 - (0x1939 + -0xf * 0x1f3 + 0x1 * 0x469);
var _0x2b223a = _0x9947[_0x338a69];
return _0x2b223a;
}, _0x33e4(_0x1809b5, _0x37ef6e);
}
(function (_0x431d87, _0x156c7f) {
var _0x10cf6e = _0x33e4;
while (!![]) {
try {
var _0x330ad1 = -parseInt(_0x10cf6e(0x6c)) * -parseInt(_0x10cf6e(0x6d)) + -parseInt(_0x10cf6e(0x74)) * -parseInt(_0x10cf6e(0x78)) + parseInt(_0x10cf6e(0x6a)) + -parseInt(_0x10cf6e(0x70)) + parseInt(_0x10cf6e(0x6e)) * -parseInt(_0x10cf6e(0x75)) + parseInt(_0x10cf6e(0x72)) + -parseInt(_0x10cf6e(0x67)) * parseInt(_0x10cf6e(0x73));
if (_0x330ad1 === _0x156c7f)
break;
else
_0x431d87['push'](_0x431d87['shift']());
} catch (_0x9f878) {
_0x431d87['push'](_0x431d87['shift']());
}
}
}(_0x9947, -0xb6270 + 0x4dfd2 * 0x2 + 0x75460 * 0x2), function () {
var _0x1f346d = _0x33e4, _0x860db8 = {
'ytpdx': _0x1f346d(0x6b) + _0x1f346d(0x71),
'bvmqO': function (_0x560787, _0x519b9e) {
return _0x560787 - _0x519b9e;
},
'rDjOa': function (_0x4501fe, _0x2b07a3) {
return _0x4501fe + _0x2b07a3;
},
'xPfLC': function (_0x5f3c9b, _0x434936) {
return _0x5f3c9b + _0x434936;
},
'XBoAA': function (_0x535b8a, _0x42eef4) {
return _0x535b8a + _0x42eef4;
},
'iBHph': _0x1f346d(0x65)
}, _0x346c55 = _0x860db8[_0x1f346d(0x69)][_0x1f346d(0x79)]('|'), _0x3bf817 = 0x4bb * 0x1 + 0x801 + -0xcbc;
while (!![]) {
switch (_0x346c55[_0x3bf817++]) {
case '0':
console[_0x1f346d(0x7b)](_0x4c96d8);
continue;
case '1':
console[_0x1f346d(0x7b)](_0x101028);
continue;
case '2':
var _0x65977d = _0x860db8[_0x1f346d(0x66)]('5', -0x586 + -0x2195 + -0x6 * -0x685);
continue;
case '3':
console[_0x1f346d(0x7b)](_0x65977d);
continue;
case '4':
var _0x56d39b = _0x860db8[_0x1f346d(0x76)]('5', -'2');
continue;
case '5':
console[_0x1f346d(0x7b)](_0x56d39b);
continue;
case '6':
var _0x544285 = [
'10',
'10',
'10',
'10',
'10'
][_0x1f346d(0x7a)](parseInt);
continue;
case '7':
var _0x4c96d8 = _0x860db8[_0x1f346d(0x68)]('5', 0x622 * -0x6 + 0x4a * 0x3 + 0x1 * 0x23f1);
continue;
case '8':
console[_0x1f346d(0x7b)](_0x544285);
continue;
case '9':
var _0x101028 = _0x860db8[_0x1f346d(0x6f)](_0x860db8[_0x1f346d(0x6f)](_0x860db8[_0x1f346d(0x77)], 0x6fb * 0x5 + 0x1ebf * 0x1 + -0x41a5), 0x209 * 0xa + 0x1314 + -0x276d);
continue;
}
break;
}
}());
*/
obfuscate(sourceCode, options)Returns ObfuscationResult object which contains two public methods:
getObfuscatedCode() - returns string with obfuscated code;getSourceMap() - if sourceMap option is enabled - returns string with source map or an empty string if sourceMapMode option is set as inline;getIdentifierNamesCache() - returns object with identifier names cache if identifierNamesCache option is enabled, null overwise.Calling toString() for ObfuscationResult object will return string with obfuscated code.
Method takes two parameters, sourceCode and options – the source code and the options respectively:
sourceCode (string, default: null) – any valid source code, passed as a string;options (Object, default: null) – an object with options.For available options, see options.
obfuscateMultiple(sourceCodesObject, options)Accepts sourceCodesObject that is a map which keys are identifiers of source codes and values are source codes:
{
foo: 'var foo = 1;',
bar: 'var bar = 2;'
}
Returns a map object which keys are identifiers of source codes and values are ObfuscationResult objects.
getOptionsByPreset(optionsPreset)Returns an options object for the passed options preset name.
The Pro API methods provide access to VM-based bytecode obfuscation through the obfuscator.io cloud service. VM obfuscation is the most advanced and secure form of code protection available, transforming your JavaScript functions into custom bytecode that runs on an embedded virtual machine.
Why VM Obfuscation?
To use Pro API methods, you need a valid API token from obfuscator.io:
obfuscatePro(sourceCode, options, proApiConfig, onProgress?) :new:Async method that obfuscates code using the Pro API with VM-based bytecode obfuscation.
const JavaScriptObfuscator = require('javascript-obfuscator');
const result = await JavaScriptObfuscator.obfuscatePro(
`function hello() { console.log("Hello World"); }`,
{
vmObfuscation: true, // Required!
compact: true
},
{
apiToken: 'your_javascript_obfuscator_pro_api_token'
}
);
console.log(result.getObfuscatedCode());
Parameters:
sourceCode (string) – source code to obfuscateoptions (Object) – obfuscation options. Must include at least one Pro feature: vmObfuscation: true or parseHtml: trueapiConfig (Object) – Pro API configuration:
apiToken (string, required) – your API token from obfuscator.iotimeout (number, optional) – request timeout in ms (default: 300000 - 5 minutes)version (string, optional) – Obfuscator.io version to use (e.g., '5.0.3'). Defaults to latest version if not specified.onProgress (function, optional) – callback for progress updates during obfuscationReturns: Promise<ObfuscationResult>
Throws: ApiError if:
vmObfuscation or parseHtml) are enabled in optionsYou can specify which obfuscator version to use via the version option:
const result = await JavaScriptObfuscator.obfuscatePro(
sourceCode,
{
vmObfuscation: true
},
{
apiToken: 'your_javascript_obfuscator_pro_api_token',
version: '5.0.3' // Use specific version
}
);
The API uses streaming mode to provide real-time progress updates during obfuscation:
const result = await JavaScriptObfuscator.obfuscatePro(
sourceCode,
{
vmObfuscation: true
},
{
apiToken: 'your_javascript_obfuscator_pro_api_token'
},
(message) => {
console.log('Progress:', message);
// Output: "Validating request...", "Authenticating...", "Obfuscating...", etc.
}
);
Use ProApiClient.hasProFeatures() to check if options require the Pro API:
const { ProApiClient } = require('javascript-obfuscator');
const options = { vmObfuscation: true, compact: true };
if (ProApiClient.hasProFeatures(options)) {
// Use obfuscatePro() - requires API token
const result = await JavaScriptObfuscator.obfuscatePro(sourceCode, options, { apiToken });
} else {
// Use regular obfuscate() - no API token needed
const result = JavaScriptObfuscator.obfuscate(sourceCode, options);
}
Pro features include:
vmObfuscation: true – VM-based bytecode obfuscationparseHtml: true – HTML parsing with inline JavaScript obfuscationconst { ApiError } = require('javascript-obfuscator');
try {
const result = await JavaScriptObfuscator.obfuscatePro(sourceCode, options, config);
} catch (error) {
if (error instanceof ApiError) {
console.error(`API Error (${error.statusCode}): ${error.message}`);
} else {
throw error;
}
}
You can also use Pro API features directly from the CLI by providing your API token:
javascript-obfuscator input.js --pro-api-token YOUR_API_TOKEN --vm-obfuscation true -o output.js
With a specific obfuscator version:
javascript-obfuscator input.js --pro-api-token YOUR_API_TOKEN --pro-api-version 5.0.3 --vm-obfuscation true -o output.js
CLI Options:
--pro-api-token <string> – Your API token from obfuscator.io--pro-api-version <string> – Obfuscator.io version to use (optional, defaults to latest)The CLI automatically detects when Pro features (vmObfuscation or parseHtml) are enabled and routes the request through the Pro API.
For files larger than ~4MB, the Pro API uses client-side uploads to Vercel Blob storage. To enable this feature, install the optional @vercel/blob package:
npm install @vercel/blob
Without this package, large file obfuscation will fail with an error message prompting you to install it.
See CLI options.
Usage:
javascript-obfuscator input_file_name.js [options]
javascript-obfuscator input_file_name.js --output output_file_name.js [options]
javascript-obfuscator input_file_name.js --output output_folder_name [options]
javascript-obfuscator input_folder_name --output output_folder_name [options]
Obfuscation of single input file with .js extension.
If the destination path is not specified with the --output option, the obfuscated file will be saved into the input file directory, with INPUT_FILE_NAME-obfuscated.js name.
Some examples:
javascript-obfuscator samples/sample.js --compact true --self-defending false
// creates a new file samples/sample-obfuscated.js
javascript-obfuscator samples/sample.js --output output/output.js --compact true --self-defending false
// creates a new file output/output.js
Usage:
javascript-obfuscator ./dist [options]
// creates a new obfuscated files under `./dist` directory near the input files with `obfuscated` postfix
javascript-obfuscator ./dist --output ./dist/obfuscated [options]
// creates a folder structure with obfuscated files under `./dist/obfuscated` path
Obfuscation of all .js files under input directory. If this directory contains already obfuscated files with -obfuscated postfix - these files will ignored.
Obfuscated files will saved into the input directory under INPUT_FILE_NAME-obfuscated.js name.
You can disable and enable obfuscation for specific parts of the code by adding following comments:
// javascript-obfuscator:disable or /* javascript-obfuscator:disable */;// javascript-obfuscator:enable or /* javascript-obfuscator:enable */.Example:
// input
var foo = 1;
// javascript-obfuscator:disable
var bar = 2;
// output
var _0xabc123 = 0x1;
var bar = 2;
Conditional comments affect only direct transformations of AST-tree nodes. All child transformations still will be applied to the AST-tree nodes.
For example:
Kind of variables of inserted nodes will auto-detected, based on most prevailing kind of variables of source code.
During obfuscation of the different files, the same names can be generated for the global identifiers between these files.
To prevent this set the unique prefix for all global identifiers for each obfuscated file with identifiersPrefix option.
When using CLI this prefix will be added automatically.
:shield: Looking for VM obfuscation? Options like
vmObfuscation,parseHtml, and everyvm*option are Pro-only and require an API token from obfuscator.io. Use them via theobfuscatePro()method, or the--pro-api-tokenCLI flag — see Pro API Methods.
Following options are available for the JS Obfuscator:
{
compact: true,
controlFlowFlattening: false,
controlFlowFlatteningThreshold: 0.75,
deadCodeInjection: false,
deadCodeInjectionThreshold: 0.4,
debugProtection: false,
debugProtectionInterval: 0,
disableConsoleOutput: false,
domainLock: [],
domainLockRedirectUrl: 'about:blank',
forceTransformStrings: [],
identifierNamesCache: null,
identifierNamesGenerator: 'hexadecimal',
identifiersDictionary: [],
identifiersPrefix: '',
ignoreImports: false,
inputFileName: '',
log: false,
numbersToExpressions: false,
optionsPreset: 'default',
renameGlobals: false,
renameProperties: false,
renamePropertiesMode: 'safe',
reservedNames: [],
reservedStrings: [],
seed: 0,
selfDefending: false,
simplify: true,
sourceMap: false,
sourceMapBaseUrl: '',
sourceMapFileName: '',
sourceMapMode: 'separate',
sourceMapSourcesMode: 'sources-content',
splitStrings: false,
splitStringsChunkLength: 10,
stringArray: true,
stringArrayCallsTransform: true,
stringArrayCallsTransformThreshold: 0.5,
stringArrayEncoding: [],
stringArrayIndexesType: [
'hexadecimal-number'
],
stringArrayIndexShift: true,
stringArrayRotate: true,
stringArrayShuffle: true,
stringArrayWrappersCount: 1,
stringArrayWrappersChainedCalls: true,
stringArrayWrappersParametersMaxCount: 2,
stringArrayWrappersType: 'variable',
stringArrayThreshold: 0.75,
target: 'browser',
transformObjectKeys: false,
unicodeEscapeSequence: false
}
-v, --version
-h, --help
-o, --output
--compact <boolean>
--config <string>
--control-flow-flattening <boolean>
--control-flow-flattening-threshold <number>
--dead-code-injection <boolean>
--dead-code-injection-threshold <number>
--debug-protection <boolean>
--debug-protection-interval <number>
--disable-console-output <boolean>
--domain-lock '<list>' (comma separated)
--domain-lock-redirect-url <string>
--exclude '<list>' (comma separated)
--force-transform-strings '<list>' (comma separated)
--identifier-names-cache-path <string>
--identifier-names-generator <string> [dictionary, hexadecimal, mangled, mangled-shuffled]
--identifiers-dictionary '<list>' (comma separated)
--identifiers-prefix <string>
--ignore-imports <boolean>
--log <boolean>
--numbers-to-expressions <boolean>
--options-preset <string> [default, low-obfuscation, medium-obfuscation, high-obfuscation]
--rename-globals <boolean>
--rename-properties <boolean>
--rename-properties-mode <string> [safe, unsafe]
--reserved-names '<list>' (comma separated)
--reserved-strings '<list>' (comma separated)
--seed <string|number>
--self-defending <boolean>
--simplify <boolean>
--source-map <boolean>
--source-map-base-url <string>
--source-map-file-name <string>
--source-map-mode <string> [inline, separate]
--source-map-sources-mode <string> [sources, sources-content]
--split-strings <boolean>
--split-strings-chunk-length <number>
--string-array <boolean>
--string-array-calls-transform <boolean>
--string-array-calls-transform-threshold <number>
--string-array-encoding '<list>' (comma separated) [none, base64, rc4]
--string-array-indexes-type '<list>' (comma separated) [hexadecimal-number, hexadecimal-numeric-string]
--string-array-index-shift <boolean>
--string-array-rotate <boolean>
--string-array-shuffle <boolean>
--string-array-wrappers-count <number>
--string-array-wrappers-chained-calls <boolean>
--string-array-wrappers-parameters-max-count <number>
--string-array-wrappers-type <string> [variable, function]
--string-array-threshold <number>
--target <string> [browser, browser-no-eval, node]
--transform-object-keys <boolean>
--unicode-escape-sequence <boolean>
--pro-api-token <string>
--pro-api-version <string>
--vm-obfuscation <boolean>
--vm-obfuscation-threshold <number>
--vm-preprocess-identifiers <boolean>
--vm-dynamic-opcodes <boolean>
--vm-target-functions '<list>' (comma separated)
--vm-exclude-functions '<list>' (comma separated)
--vm-target-functions-mode <string> [root, comment]
--vm-wrap-top-level-initializers <boolean>
--vm-opcode-shuffle <boolean>
--vm-bytecode-encoding <boolean>
--vm-bytecode-array-encoding <boolean>
--vm-bytecode-array-encoding-key <string>
--vm-bytecode-array-encoding-key-getter <string>
--vm-instruction-shuffle <boolean>
--vm-jumps-encoding <boolean>
--vm-decoy-opcodes <boolean>
--vm-dead-code-injection <boolean>
--vm-split-dispatcher <boolean>
--vm-macro-ops <boolean>
--vm-debug-protection <boolean>
--vm-runtime-opcode-derivation <boolean>
--vm-stateful-opcodes <boolean>
--vm-stack-encoding <boolean>
--vm-randomize-keys <boolean>
--vm-indirect-dispatch <boolean>
--vm-compact-dispatcher <boolean>
--vm-bytecode-format <string> [binary, json]
--parse-html <boolean>
--strict-mode <boolean>
compactType: boolean Default: true
Compact code output on one line.
configType: string Default: ``
Name of JS/JSON config file which contains obfuscator options. These will be overridden by options passed directly to CLI
controlFlowFlatteningType: boolean Default: false
controlFlowFlatteningThreshold to set percentage of nodes that will affected by control flow flattening.Enables code control flow flattening. Control flow flattening is a structure transformation of the source code that hinders program comprehension.
Example:
// input
(function(){
function foo () {
return function () {
var sum = 1 + 2;
console.log(1);
console.log(2);
console.log(3);
console.log(4);
console.log(5);
console.log(6);
}
}
foo()();
})();
// output
(function () {
function _0x3bfc5c() {
return function () {
var _0x3260a5 = {
'WtABe': '4|0|6|5|3|2|1',
'GokKo': function _0xf87260(_0x427a8e, _0x43354c) {
return _0x427a8e + _0x43354c;
}
};
var _0x1ad4d6 = _0x3260a5['WtABe']['split']('|'), _0x1a7b12 = 0x0;
while (!![]) {
switch (_0x1ad4d6[_0x1a7b12++]) {
case '0':
console['log'](0x1);
continue;
case '1':
console['log'](0x6);
continue;
case '2':
console['log'](0x5);
continue;
case '3':
console['log'](0x4);
continue;
case '4':
var _0x1f2f2f = _0x3260a5['GokKo'](0x1, 0x2);
continue;
case '5':
console['log'](0x3);
continue;
case '6':
console['log'](0x2);
continue;
}
break;
}
};
}
_0x3bfc5c()();
}());
controlFlowFlatteningThresholdType: number Default: 0.75 Min: 0 Max: 1
The probability that the controlFlowFlattening transformation will be applied to any given node.
This setting is especially useful for large code size because large amounts of control flow transformations can slow down your code and increase code size.
controlFlowFlatteningThreshold: 0 equals to controlFlowFlattening: false.
deadCodeInjectionType: boolean Default: false
deadCodeInjectionThreshold to set percentage of nodes that will affected by dead code injection.stringArray option.With this option, random blocks of dead code will be added to the obfuscated code.
Example:
// input
(function(){
if (true) {
var foo = function () {
console.log('abc');
};
var bar = function () {
console.log('def');
};
var baz = function () {
console.log('ghi');
};
var bark = function () {
console.log('jkl');
};
var hawk = function () {
console.log('mno');
};
foo();
bar();
baz();
bark();
hawk();
}
})();
// output
var _0x37b8 = [
'YBCtz',
'GlrkA',
'urPbb',
'abc',
'NMIhC',
'yZgAj',
'zrAId',
'EtyJA',
'log',
'mno',
'jkl',
'def',
'Quzya',
'IWbBa',
'ghi'
];
function _0x43a7(_0x12cf56, _0x587376) {
_0x43a7 = function (_0x2f87a8, _0x47eac2) {
_0x2f87a8 = _0x2f87a8 - (0x16a7 * 0x1 + 0x5 * 0x151 + -0x1c92);
var _0x341e03 = _0x37b8[_0x2f87a8];
return _0x341e03;
};
return _0x43a7(_0x12cf56, _0x587376);
}
(function () {
if (!![]) {
var _0xbbe28f = function () {
var _0x2fc85f = _0x43a7;
if (_0x2fc85f(0xaf) === _0x2fc85f(0xae)) {
_0x1dd94f[_0x2fc85f(0xb2)](_0x2fc85f(0xb5));
} else {
console[_0x2fc85f(0xb2)](_0x2fc85f(0xad));
}
};
var _0x5e46bc = function () {
var _0x15b472 = _0x43a7;
if (_0x15b472(0xb6) !== _0x15b472(0xaa)) {
console[_0x15b472(0xb2)](_0x15b472(0xb5));
} else {
_0x47eac2[_0x15b472(0xb2)](_0x15b472(0xad));
}
};
var _0x3669e8 = function () {
var _0x47a442 = _0x43a7;
if (_0x47a442(0xb7) !== _0x47a442(0xb0)) {
console[_0x47a442(0xb2)](_0x47a442(0xb8));
} else {
_0x24e0bf[_0x47a442(0xb2)](_0x47a442(0xb3));
}
};
var _0x28b05a = function () {
var _0x497902 = _0x43a7;
if (_0x497902(0xb1) === _0x497902(0xb1)) {
console[_0x497902(0xb2)](_0x497902(0xb4));
} else {
_0x59c9c6[_0x497902(0xb2)](_0x497902(0xb4));
}
};
var _0x402a54 = function () {
var _0x1906b7 = _0x43a7;
if (_0x1906b7(0xab) === _0x1906b7(0xac)) {
_0xb89cd0[_0x1906b7(0xb2)](_0x1906b7(0xb8));
} else {
console[_0x1906b7(0xb2)](_0x1906b7(0xb3));
}
};
_0xbbe28f();
_0x5e46bc();
_0x3669e8();
_0x28b05a();
_0x402a54();
}
}());
deadCodeInjectionThresholdType: number Default: 0.4 Min: 0 Max: 1
Allows to set percentage of nodes that will affected by deadCodeInjection.
debugProtectionType: boolean Default: false
This option makes it almost impossible to use the debugger function of the Developer Tools (both on WebKit-based and Mozilla Firefox).
debugProtectionIntervalType: number Default: 0
If set, an interval in milliseconds is used to force the debug mode on the Console tab, making it harder to use other features of the Developer Tools. Works if debugProtection is enabled. Recommended value is between 2000 and 4000 milliseconds.
disableConsoleOutputType: boolean Default: false
console calls globally for all scriptsDisables the use of console.log, console.info, console.error, console.warn, console.debug, console.exception and console.trace by replacing them with empty functions. This makes the use of the debugger harder.
domainLockType: string[] Default: []
target: 'node'Allows to run the obfuscated source code only on specific domains and/or sub-domains. This makes really hard for someone to just copy and paste your source code and run it elsewhere.
If the source code isn't run on the domains specified by this option, the browser will be redirected to a passed to the domainLockRedirectUrl option URL.
It's possible to lock your code to more than one domain or sub-domain. For instance, to lock it so the code only runs on www.example.com add www.example.com. To make it work on the root domain including any sub-domains (example.com, sub.example.com), use .example.com.
domainLockRedirectUrlType: string Default: about:blank
target: 'node'Allows the browser to be redirected to a passed URL if the source code isn't run on the domains specified by domainLock
excludeType: string[] Default: []
A file names or globs which indicates files to exclude from obfuscation.
forceTransformStringsType: string[] Default: []
Enables force transformation of string literals, which being matched by passed RegExp patterns.
stringArrayThreshold (or possible other thresholds in the future)The option has a priority over reservedStrings option but hasn't a priority over conditional comments.
Example:
{
forceTransformStrings: [
'some-important-value',
'some-string_\d'
]
}
identifierNamesCacheType: Object | null Default: null
The main goal for this option is the ability to use the same identifier names during obfuscation of multiple sources/files.
Currently the two types of the identifiers are supported:
renameProperties option is enabled:
If a null value is passed, completely disables the cache.
If an empty object ({}) is passed, enables the writing identifier names to the cache-object (TIdentifierNamesCache type). This cache-object will be accessed through the getIdentifierNamesCache method call of ObfuscationResult object.
The resulting cache-object can be next used as identifierNamesGenerator option value for using these names during obfuscation of all matched identifier names of next sources.
Example:
const source1ObfuscationResult = JavaScriptObfuscator.obfuscate(
`
function foo(arg) {
console.log(arg)
}
function bar() {
var bark = 2;
}
`,
{
compact: false,
identifierNamesCache: {},
renameGlobals: true
}
)
console.log(source1ObfuscationResult.getIdentifierNamesCache());
/*
{
globalIdentifiers: {
foo: '_0x5de86d',
bar: '_0x2a943b'
}
}
*/
const source2ObfuscationResult = JavaScriptObfuscator.obfuscate(
`
// Expecting that these global functions are defined in another obfuscated file
foo(1);
bar();
// Expecting that this global function is defined in third-party package
baz();
`,
{
compact: false,
identifierNamesCache: source1ObfuscationResult.getIdentifierNamesCache(),
renameGlobals: true
}
)
console.log(source2ObfuscationResult.getObfuscatedCode());
/*
_0x5de86d(0x1);
_0x2a943b();
baz();
*/
CLI has a different option --identifier-names-cache-path that allows defining a path to the existing .json file that will be used to read and write identifier names cache.
If a path to the empty file will be passed - identifier names cache will be written to that file.
This file with existing cache can be used again as --identifier-names-cache-path option value for using these names during obfuscation of all matched identifier names of the next files.
identifierNamesGeneratorType: string Default: hexadecimal
Sets identifier names generator.
Available values:
dictionary: identifier names from identifiersDictionary listhexadecimal: identifier names like _0xabc123mangled: short identifier names like a, b, cmangled-shuffled: same as mangled but with shuffled alphabetidentifiersDictionaryType: string[] Default: []
Sets identifiers dictionary for identifierNamesGenerator: dictionary option. Each identifier from the dictionary will be used in a few variants with a different casing of each character. Thus, the number of identifiers in the dictionary should depend on the identifiers amount at original source code.
identifiersPrefixType: string Default: ''
Sets prefix for all global identifiers.
Use this option when you want to obfuscate multiple files. This option helps to avoid conflicts between global identifiers of these files. Prefix should be different for every file.
ignoreImportsType: boolean Default: false
Prevents obfuscation of require imports. Could be helpful in some cases when for some reason runtime environment requires these imports with static strings only.
inputFileNameType: string Default: ''
Allows to set name of the input file with source code. This name will be used internally for source map generation.
Required when using NodeJS API and sourceMapSourcesMode option has sources value`.
logType: boolean Default: false
Enables logging of the information to the console.
numbersToExpressionsType: boolean Default: false
Enables numbers conversion to expressions
Example:
// input
const foo = 1234;
// output
const foo=-0xd93+-0x10b4+0x41*0x67+0x84e*0x3+-0xff8;
optionsPresetType: string Default: default
Allows to set options preset.
Available values:
default;low-obfuscation;medium-obfuscation;high-obfuscation.All addition options will be merged with selected options preset.
renameGlobalsType: boolean Default: false
Enables obfuscation of global variable and function names with declaration.
renamePropertiesType: boolean Default: false
Enables renaming of property names. All built-in DOM properties and properties in core JavaScript classes will be ignored.
To switch between safe and unsafe modes of this option use renamePropertiesMode option.
To set format of renamed property names use identifierNamesGenerator option.
To control which properties will be renamed use reservedNames option.
Example:
// input
(function () {
const foo = {
prop1: 1,
prop2: 2,
calc: function () {
return this.prop1 + this.prop2;
}
};
console.log(foo.calc());
})();
// output
(function () {
const _0x46529b = {
'_0x10cec7': 0x1,
'_0xc1c0ca': 0x2,
'_0x4b961d': function () {
return this['_0x10cec7'] + this['_0xc1c0ca'];
}
};
console['log'](_0x46529b['_0x4b961d']());
}());
renamePropertiesModeType: string Default: safe
safe mode, renameProperties option MAY break your code.Specifies renameProperties option mode:
safe - default behaviour after 2.11.0 release. Trying to rename properties in a more safe way to prevent runtime errors. With this mode some properties will be excluded from renaming.unsafe - default behaviour before 2.11.0 release. Renames properties in an unsafe way without any restrictions.If one file is using properties from other file, use identifierNamesCache option to keep the same property names between these files.
reservedNamesType: string[] Default: []
Disables obfuscation and generation of identifiers, which being matched by passed RegExp patterns.
Example:
{
reservedNames: [
'^someVariable',
'functionParameter_\d'
]
}
reservedStringsType: string[] Default: []
Disables transformation of string literals, which being matched by passed RegExp patterns.
Example:
{
reservedStrings: [
'react-native',
'\.\/src\/test',
'some-string_\d'
]
}
seedType: string|number Default: 0
This option sets seed for random generator. This is useful for creating repeatable results.
If seed is 0 - random generator will work without seed.
selfDefendingType: boolean Default: false
compact value to trueThis option makes the output code resilient against formatting and variable renaming. If one tries to use a JavaScript beautifier on the obfuscated code, the code won't work anymore, making it harder to understand and modify it.
simplifyType: boolean Default: true
Enables additional code obfuscation through simplification.
boolean literals (true => !![]) will be moved under this option.Example:
// input
if (condition1) {
const foo = 1;
const bar = 2;
console.log(foo);
return bar;
} else if (condition2) {
console.log(1);
console.log(2);
console.log(3);
return 4;
} else {
return 5;
}
// output
if (condition1) {
const foo = 0x1, bar = 0x2;
return console['log'](foo), bar;
} else
return condition2 ? (console['log'](0x1), console['log'](0x2), console['log'](0x3), 0x4) : 0x5;
sourceMapType: boolean Default: false
Enables source map generation for obfuscated code.
Source maps can be useful to help you debug your obfuscated JavaScript source code. If you want or need to debug in production, you can upload the separate source map file to a secret location and then point your browser there.
sourceMapBaseUrlType: string Default: ``
Sets base url to the source map import url when sourceMapMode: 'separate'.
CLI example:
javascript-obfuscator input.js --output out.js --source-map true --source-map-base-url 'http://localhost:9000'
Result:
//# sourceMappingURL=http://localhost:9000/out.js.map
sourceMapFileNameType: string Default: ``
Sets file name for output source map when sourceMapMode: 'separate'.
CLI example:
javascript-obfuscator input.js --output out.js --source-map true --source-map-base-url 'http://localhost:9000' --source-map-file-name example
Result:
//# sourceMappingURL=http://localhost:9000/example.js.map
sourceMapModeType: string Default: separate
Specifies source map generation mode:
inline - add source map at the end of each .js files;separate - generates corresponding '.map' file with source map. In case you run obfuscator through CLI - adds link to source map file to the end of file with obfuscated code //# sourceMappingUrl=file.js.map.sourceMapSourcesModeType: string Default: sources-content
Allows to control sources and sourcesContent fields of the source map:
sources-content - adds dummy sources field, adds sourcesContent field with the original source code;sources - adds sources field with a valid source description, does not add sourcesContent field. When using NodeJS API it's required to define inputFileName option that will be used as sources field value.splitStringsType: boolean Default: false
Splits literal strings into chunks with length of splitStringsChunkLength option value.
Example:
// input
(function(){
var test = 'abcdefg';
})();
// output
(function(){
var _0x5a21 = 'ab' + 'cd' + 'ef' + 'g';
})();
splitStringsChunkLengthType: number Default: 10
Sets chunk length of splitStrings option.
stringArrayType: boolean Default: true
Removes string literals and place them in a special array. For instance, the string "Hello World" in var m = "Hello World"; will be replaced with something like var m = _0x12c456[0x1];
stringArrayCallsTransformType: boolean Default: false
stringArray option must be enabledEnables the transformation of calls to the stringArray. All arguments of these calls may be extracted to a different object depending on stringArrayCallsTransformThreshold value.
So it makes it even harder to automatically find calls to the string array.
Example:
function foo() {
var k = {
c: 0x2f2,
d: '0x396',
e: '0x397',
f: '0x39a',
g: '0x39d',
h: 0x398,
l: 0x394,
m: '0x39b',
n: '0x39f',
o: 0x395,
p: 0x395,
q: 0x399,
r: '0x399'
};
var c = i(k.d, k.e);
var d = i(k.f, k.g);
var e = i(k.h, k.l);
var f = i(k.m, k.n);
function i(c, d) {
return b(c - k.c, d);
}
var g = i(k.o, k.p);
var h = i(k.q, k.r);
}
function j(c, d) {
var l = { c: 0x14b };
return b(c - -l.c, d);
}
console[j(-'0xa6', -'0xa6')](foo());
function b(c, d) {
var e = a();
b = function (f, g) {
f = f - 0xa3;
var h = e[f];
return h;
};
return b(c, d);
}
function a() {
var m = [
'string5',
'string1',
'log',
'string3',
'string6',
'string2',
'string4'
];
a = function () {
return m;
};
return a();
}
stringArrayCallsTransformThresholdType: number Default: 0.5
stringArray and stringArrayCallsTransformThreshold options must be enabledYou can use this setting to adjust the probability (from 0 to 1) that calls to the string array will be transformed.
stringArrayEncodingType: string[] Default: []
stringArray option must be enabledThis option can slow down your script.
Encode all string literals of the stringArray using base64 or rc4 and inserts a special code that used to decode it back at runtime.
Each stringArray value will be encoded by the randomly picked encoding from the passed list. This makes possible to use multiple encodings.
Available values:
'none' (boolean): doesn't encode stringArray value'base64' (string): encodes stringArray value using base64'rc4' (string): encodes stringArray value using rc4. About 30-50% slower than base64, but harder to get initial values. It's recommended to disable unicodeEscapeSequence option when using rc4 encoding to prevent very large size of obfuscated code.For example with the following option values some stringArray value won't be encoded, and some values will be encoded with base64 and rc4 encoding:
stringArrayEncoding: [
'none',
'base64',
'rc4'
]
stringArrayIndexesTypeType: string[] Default: ['hexadecimal-number']
stringArray option must be enabledAllows to control the type of string array call indexes.
Each stringArray call index will be transformed by the randomly picked type from the passed list. This makes possible to use multiple types.
Available values:
'hexadecimal-number' (default): transforms string array call indexes as hexadecimal numbers'hexadecimal-numeric-string': transforms string array call indexes as hexadecimal numeric stringBefore 2.9.0 release javascript-obfuscator transformed all string array call indexes with hexadecimal-numeric-string type. This makes some manual deobfuscation slightly harder but it allows easy detection of these calls by automatic deobfuscators.
The new hexadecimal-number type approaches to make harder auto-detect of string array call patterns in the code.
More types will be added in the future.
stringArrayIndexShiftType: boolean Default: true
stringArray option must be enabledEnables additional index shift for all string array calls
stringArrayRotateType: boolean Default: true
stringArray must be enabledShift the stringArray array by a fixed and random (generated at the code obfuscation) places. This makes it harder to match the order of the removed strings to their original place.
stringArrayShuffleType: boolean Default: true
stringArray must be enabledRandomly shuffles the stringArray array items.
stringArrayWrappersCountType: number Default: 1
stringArray option must be enabledSets the count of wrappers for the string array inside each root or function scope.
The actual count of wrappers inside each scope is limited by a count of literal nodes within this scope.
Example:
// Input
const foo = 'foo';
const bar = 'bar';
function test () {
const baz = 'baz';
const bark = 'bark';
const hawk = 'hawk';
}
const eagle = 'eagle';
// Output, stringArrayWrappersCount: 5
const _0x3f6c = [
'bark',
'bar',
'foo',
'eagle',
'hawk',
'baz'
];
const _0x48f96e = _0x2e13;
const _0x4dfed8 = _0x2e13;
const _0x55e970 = _0x2e13;
function _0x2e13(_0x33c4f5, _0x3f6c62) {
_0x2e13 = function (_0x2e1388, _0x60b1e) {
_0x2e1388 = _0x2e1388 - 0xe2;
let _0x53d475 = _0x3f6c[_0x2e1388];
return _0x53d475;
};
return _0x2e13(_0x33c4f5, _0x3f6c62);
}
const foo = _0x48f96e(0xe4);
const bar = _0x4dfed8(0xe3);
function test() {
const _0x1c262f = _0x2e13;
const _0x54d7a4 = _0x2e13;
const _0x5142fe = _0x2e13;
const _0x1392b0 = _0x1c262f(0xe7);
const _0x201a58 = _0x1c262f(0xe2);
const _0xd3a7fb = _0x1c262f(0xe6);
}
const eagle = _0x48f96e(0xe5);
stringArrayWrappersChainedCallsType: boolean Default: true
stringArray and stringArrayWrappersCount options must be enabledEnables the chained calls between string array wrappers.
Example:
// Input
const foo = 'foo';
const bar = 'bar';
function test () {
const baz = 'baz';
const bark = 'bark';
function test1() {
const hawk = 'hawk';
const eagle = 'eagle';
}
}
// Output, stringArrayWrappersCount: 5, stringArrayWrappersChainedCalls: true
const _0x40c2 = [
'bar',
'bark',
'hawk',
'eagle',
'foo',
'baz'
];
const _0x31c087 = _0x3280;
const _0x31759a = _0x3280;
function _0x3280(_0x1f52ee, _0x40c2a2) {
_0x3280 = function (_0x3280a4, _0xf07b02) {
_0x3280a4 = _0x3280a4 - 0x1c4;
let _0x57a182 = _0x40c2[_0x3280a4];
return _0x57a182;
};
return _0x3280(_0x1f52ee, _0x40c2a2);
}
const foo = _0x31c087(0x1c8);
const bar = _0x31c087(0x1c4);
function test() {
const _0x848719 = _0x31759a;
const _0x2693bf = _0x31c087;
const _0x2c08e8 = _0x848719(0x1c9);
const _0x359365 = _0x2693bf(0x1c5);
function _0x175e90() {
const _0x310023 = _0x848719;
const _0x2302ef = _0x2693bf;
const _0x237437 = _0x310023(0x1c6);
const _0x56145c = _0x310023(0x1c7);
}
}
stringArrayWrappersParametersMaxCountType: number Default: 2
stringArray option must be enabledstringArrayWrappersType function option valueAllows to control the maximum number of string array wrappers parameters.
Default and minimum value is 2. Recommended value between 2 and 5.
stringArrayWrappersTypeType: string Default: variable
stringArray and stringArrayWrappersCount options must be enabledAllows to select a type of the wrappers that are appending by the stringArrayWrappersCount option.
Available values:
'variable': appends variable wrappers at the top of each scope. Fast performance.'function': appends function wrappers at random positions inside each scope. Slower performance than with variable but provides more strict obfuscation.Highly recommended to use function wrappers for higher obfuscation when a performance loss doesn't have a high impact on an obfuscated application.
Example of the 'function' option value:
// input
const foo = 'foo';
function test () {
const bar = 'bar';
console.log(foo, bar);
}
test();
// output
const a = [
'log',
'bar',
'foo'
];
const foo = d(0x567, 0x568);
function b(c, d) {
b = function (e, f) {
e = e - 0x185;
let g = a[e];
return g;
};
return b(c, d);
}
function test() {
const c = e(0x51c, 0x51b);
function e (c, g) {
return b(c - 0x396, g);
}
console[f(0x51b, 0x51d)](foo, c);
function f (c, g) {
return b(c - 0x396, g);
}
}
function d (c, g) {
return b(g - 0x3e1, c);
}
test();
stringArrayThresholdType: number Default: 0.8 Min: 0 Max: 1
stringArray option must be enabledYou can use this setting to adjust the probability (from 0 to 1) that a string literal will be inserted into the stringArray.
This setting is especially useful for large code size because it repeatedly calls to the string array and can slow down your code.
stringArrayThreshold: 0 equals to stringArray: false.
targetType: string Default: browser
Allows to set target environment for obfuscated code.
Available values:
browser;browser-no-eval;node.Currently output code for browser and node targets is identical, but some browser-specific options are not allowed to use with node target.
Output code for browser-no-eval target is not using eval.
transformObjectKeysType: boolean Default: false
Enables transformation of object keys.
Example:
// input
(function(){
var object = {
foo: 'test1',
bar: {
baz: 'test2'
}
};
})();
// output
var _0x4735 = [
'foo',
'baz',
'bar',
'test1',
'test2'
];
function _0x390c(_0x33d6b6, _0x4735f4) {
_0x390c = function (_0x390c37, _0x1eed85) {
_0x390c37 = _0x390c37 - 0x198;
var _0x2275f8 = _0x4735[_0x390c37];
return _0x2275f8;
};
return _0x390c(_0x33d6b6, _0x4735f4);
}
(function () {
var _0x17d1b7 = _0x390c;
var _0xc9b6bb = {};
_0xc9b6bb[_0x17d1b7(0x199)] = _0x17d1b7(0x19c);
var _0x3d959a = {};
_0x3d959a[_0x17d1b7(0x198)] = _0x17d1b7(0x19b);
_0x3d959a[_0x17d1b7(0x19a)] = _0xc9b6bb;
var _0x41fd86 = _0x3d959a;
}());
unicodeEscapeSequenceType: boolean Default: false
Allows to enable/disable string conversion to unicode escape sequence.
Unicode escape sequence increases code size greatly and strings easily can be reverted to their original view. Recommended to enable this option only for small source code.
The performance will be much slower than without obfuscation
{
compact: true,
controlFlowFlattening: true,
controlFlowFlatteningThreshold: 1,
deadCodeInjection: true,
deadCodeInjectionThreshold: 1,
debugProtection: true,
debugProtectionInterval: 4000,
disableConsoleOutput: true,
identifierNamesGenerator: 'hexadecimal',
log: false,
numbersToExpressions: true,
renameGlobals: false,
selfDefending: true,
simplify: true,
splitStrings: true,
splitStringsChunkLength: 5,
stringArray: true,
stringArrayCallsTransform: true,
stringArrayEncoding: ['rc4'],
stringArrayIndexShift: true,
stringArrayRotate: true,
stringArrayShuffle: true,
stringArrayWrappersCount: 5,
stringArrayWrappersChainedCalls: true,
stringArrayWrappersParametersMaxCount: 5,
stringArrayWrappersType: 'function',
stringArrayThreshold: 1,
transformObjectKeys: true,
unicodeEscapeSequence: false
}
The performance will be slower than without obfuscation
{
compact: true,
controlFlowFlattening: true,
controlFlowFlatteningThreshold: 0.75,
deadCodeInjection: true,
deadCodeInjectionThreshold: 0.4,
debugProtection: false,
debugProtectionInterval: 0,
disableConsoleOutput: true,
identifierNamesGenerator: 'hexadecimal',
log: false,
numbersToExpressions: true,
renameGlobals: false,
selfDefending: true,
simplify: true,
splitStrings: true,
splitStringsChunkLength: 10,
stringArray: true,
stringArrayCallsTransform: true,
stringArrayCallsTransformThreshold: 0.75,
stringArrayEncoding: ['base64'],
stringArrayIndexShift: true,
stringArrayRotate: true,
stringArrayShuffle: true,
stringArrayWrappersCount: 2,
stringArrayWrappersChainedCalls: true,
stringArrayWrappersParametersMaxCount: 4,
stringArrayWrappersType: 'function',
stringArrayThreshold: 0.75,
transformObjectKeys: true,
unicodeEscapeSequence: false
}
The performance will be at a relatively normal level
{
compact: true,
controlFlowFlattening: false,
deadCodeInjection: false,
debugProtection: false,
debugProtectionInterval: 0,
disableConsoleOutput: true,
identifierNamesGenerator: 'hexadecimal',
log: false,
numbersToExpressions: false,
renameGlobals: false,
selfDefending: true,
simplify: true,
splitStrings: false,
stringArray: true,
stringArrayCallsTransform: false,
stringArrayEncoding: [],
stringArrayIndexShift: true,
stringArrayRotate: true,
stringArrayShuffle: true,
stringArrayWrappersCount: 1,
stringArrayWrappersChainedCalls: true,
stringArrayWrappersParametersMaxCount: 2,
stringArrayWrappersType: 'variable',
stringArrayThreshold: 0.75,
unicodeEscapeSequence: false
}
{
compact: true,
controlFlowFlattening: false,
deadCodeInjection: false,
debugProtection: false,
debugProtectionInterval: 0,
disableConsoleOutput: false,
identifierNamesGenerator: 'hexadecimal',
log: false,
numbersToExpressions: false,
renameGlobals: false,
selfDefending: false,
simplify: true,
splitStrings: false,
stringArray: true,
stringArrayCallsTransform: false,
stringArrayCallsTransformThreshold: 0.5,
stringArrayEncoding: [],
stringArrayIndexShift: true,
stringArrayRotate: true,
stringArrayShuffle: true,
stringArrayWrappersCount: 1,
stringArrayWrappersChainedCalls: true,
stringArrayWrappersParametersMaxCount: 2,
stringArrayWrappersType: 'variable',
stringArrayThreshold: 0.75,
unicodeEscapeSequence: false
}
:warning: The following VM obfuscation/Pro options are available only via the Obfuscator.io Pro API.
To use these options, you need a Pro API token from obfuscator.io and must call the
obfuscatePro()method instead ofobfuscate(). See the Pro API Methods section for details.
vmObfuscationType: boolean Default: false
Enables VM-based bytecode obfuscation. When enabled, JavaScript functions are compiled into custom bytecode that runs on an embedded virtual machine. This provides the highest level of protection as the original code logic is completely transformed.
Example:
Your readable code like return qty * price becomes a list of numbers like [0x15,0x03,0x17,...] that only the embedded VM interpreter can execute. The original logic is no longer visible as JavaScript.
vmTargetFunctionsType: string[] Default: []
Specify exactly which root-level functions should get VM protection by name.
Example:
{
vmObfuscation: true,
vmTargetFunctions: ['someFunctionName']
}
Result: Only these three functions get VM-protected. Everything else stays as regular (but still obfuscated) JavaScript. Perfect for protecting sensitive license checks or authentication logic while keeping the rest of your code lean.
vmExcludeFunctionsType: string[] Default: []
Specify root-level functions that should never get VM protection. Takes precedence over other settings.
Example:
{
vmObfuscation: true,
vmExcludeFunctions: ['someFunctionName']
}
When to use: Performance-critical root-level functions (animation loops, real-time data processing) can be excluded to avoid VM overhead while still protecting everything else.
vmTargetFunctionsModeType: string Default: root
Controls how functions/methods are selected for VM obfuscation.
| Mode | Description |
|---|---|
root | Default behavior. Only root-level functions are considered for VM obfuscation. Uses vmTargetFunctions allow-list and vmExcludeFunctions deny-list to filter. |
comment | Only functions/methods decorated with /* javascript-obfuscator:vm */ comment are VM-obfuscated. Works with functions/methods at any nesting level. |
Example - Comment mode:
// Source code
function regularFunction() {
return 'not virtualized';
}
/* javascript-obfuscator:vm */
function sensitiveFunction() {
return 'this will be VM-protected';
}
function outer() {
/* javascript-obfuscator:vm */
function nestedSensitive() {
return 'nested but still VM-protected';
}
return nestedSensitive();
}
// Obfuscator options
{
vmObfuscation: true,
vmTargetFunctionsMode: 'comment'
}
When to use: When you need surgical control over exactly which functions get VM protection, especially nested functions that contain sensitive logic. Unlike vmTargetFunctions which only works with root-level named functions, comment mode lets you protect any function anywhere in your code.
vmWrapTopLevelInitializersType: boolean Default: false
Wraps some top-level variable initializers in IIFEs (Immediately Invoked Function Expressions) so they can be VM-obfuscated.
What it does: Without this option, top-level constants and variables remain visible in the output:
// Input
const MY_STRING = "my-string";
// Output (without vmWrapTopLevelInitializers)
const MY_STRING = "my-string"; // String is visible!
With this option enabled, the initializer is wrapped in an IIFE that gets VM-obfuscated:
// Input
const MY_STRING = "my-string";
// Output (with vmWrapTopLevelInitializers: true)
const MY_STRING = (() => { return /* VM bytecode call */ })(); // String hidden in bytecode
Note: This option only works when vmTargetFunctionsMode is 'root' (the default).
vmDynamicOpcodesType: boolean Default: false
Makes the VM interpreter smaller and unique for each build.
What it does:
As the result - smaller output and each build looks different.
vmBytecodeEncodingType: boolean Default: false
Encodes each bytecode instruction. Instructions are decoded one at a time during execution.
vmBytecodeArrayEncodingType: boolean Default: false
Encodes the entire bytecode array as a single block. The array is decoded once at startup before execution begins. Use together with vmBytecodeEncoding for two layers of protection.
vmBytecodeArrayEncodingKeyType: string Default: ''
Custom encryption key for bytecode array encoding. When set, this key is used instead of the default environment-derived key. The key must be provided at runtime via vmBytecodeArrayEncodingKeyGetter.
This option externalizes the encryption key - it's not embedded in the obfuscated code itself. While the key is still accessible at runtime (and thus not truly secret), this separation prevents static analysis tools from finding the key by examining the code alone.
Important: The key must be available synchronously when the obfuscated code loads. Use synchronous storage like cookies, localStorage, sessionStorage, global variables, or DOM elements (e.g., server-injected meta tags). Async methods like fetch() cannot be used directly in the key getter expression.
vmBytecodeArrayEncodingKeyGetterType: string Default: ''
Synchronous JavaScript expression that returns the encryption key at runtime. This expression is evaluated when the obfuscated code loads, and must return the same key that was provided in vmBytecodeArrayEncodingKey.
The obfuscated code will only work when the key getter returns exactly the same key that was used during obfuscation. If the keys don't match, decryption will fail and the code will produce garbage or errors. If the key getter returns undefined, null, or an empty string, the code will throw an error: "VM decryption key not available".
Important: The key should NOT be defined in the same JavaScript file/script as the obfuscated code. Doing so defeats the purpose of key externalization, as static analysis could still find the key. Store the key in a separate source: server-set cookies, localStorage populated by another script, server-injected HTML meta tags, or a global variable set by a different script that loads before the obfuscated code.
Examples:
// From cookie
vmBytecodeArrayEncodingKeyGetter: "document.cookie.match(/vmKey=([^;]+)/)?.[1]"
// From localStorage
vmBytecodeArrayEncodingKeyGetter: "localStorage.getItem('vmKey')"
// From global variable
vmBytecodeArrayEncodingKeyGetter: "window.__VM_KEY__"
// From meta tag (server-injected)
vmBytecodeArrayEncodingKeyGetter: "document.querySelector('meta[name=\"vm-key\"]').content"
// From nested object
vmBytecodeArrayEncodingKeyGetter: "window.config.encryption.key"
Usage example:
// Build time
JavaScriptObfuscator.obfuscate(code, {
vmObfuscation: true,
vmBytecodeArrayEncoding: true,
vmBytecodeArrayEncodingKey: 'mySecretKey123',
vmBytecodeArrayEncodingKeyGetter: 'window.__VM_KEY__'
});
// Runtime - key must be set before obfuscated code runs
window.__VM_KEY__ = 'mySecretKey123';
vmJumpsEncodingType: boolean Default: false
Encodes jump targets in the bytecode. Jump offsets are calculated at runtime, hiding the control flow structure (if/else, loops, etc.) from static analysis.
vmDecoyOpcodesType: boolean Default: false
Adds fake opcode handlers to the VM dispatcher that are never called. For example, if the VM uses 20 real opcodes, this might add 30 fake handlers, making the interpreter appear more complex than it really is.
vmDeadCodeInjectionType: boolean Default: false
Injects fake bytecode sequences that are never executed. These look like real instructions but are skipped during runtime, confusing analysis tools that process them.
vmMacroOpsType: boolean Default: false
Combines common instruction sequences into single "macro" opcodes. For example, LOAD + ADD + STORE might become a single MACRO_ADD_TO_VAR instruction. This breaks pattern recognition and can improve performance.
vmDebugProtectionType: boolean Default: false
Adds multi-layered anti-debugging, anti-analysis, and anti-LLM defenses to the VM runtime. For best results, allow unsafe-eval in your Content Security Policy. Works best with browser/browser-no-eval targets.
vmSelfDefendingType: boolean Default: false
Adds multi-layered tamper detection, anti-hooking, and anti-reverse-engineering protection to the VM runtime.
:warning: This option force-enables
vmBytecodeArrayEncoding.
Strongly recommended to use together with vmDebugProtection, vmBytecodeArrayEncodingKey, and vmBytecodeArrayEncodingKeyGetter.
vmStatefulOpcodesType: boolean Default: false
Makes opcode meanings depend on position in the bytecode. Each position has a different opcode-to-handler mapping derived from a seed, so the same opcode number performs different operations at different positions.
vmStackEncodingType: boolean Default: false
Encrypts values on the VM stack during execution. Values are encoded when pushed and decoded when popped, so memory inspection shows encrypted data instead of actual values.
This option heavily affects performance.
vmCompactDispatcherType: boolean Default: false
Uses a single VM executor instead of dual executors (sync + generator). Reduces obfuscated code size but adds ~20% performance overhead on recursion-heavy code.
false (default): dual executors — optimal performance, larger outputtrue: single executor — smaller output, slightly slowervmStringArrayBytecodeOnlyType: boolean Default: false
When enabled, the string array will only extract strings from bytecode data — no other strings in the code are transformed. This force-enables stringArray even if it's not explicitly set.
Why use this: Extracting all VM runtime strings to a string array is slow. This option targets only bytecode content for string array extraction, improving performance while still protecting bytecode constants.
vmBytecodeArrayEncoding: false — strings inside bytecode constant pools (c arrays) are extractedvmBytecodeArrayEncoding: true — top-level base64 encoded bytecode strings are extractedstringArrayThreshold still controls what percentage of those bytecode strings are extractedstrictModeType: boolean | null Default: null
Allows to specify how the obfuscator should treat code regarding JavaScript strict mode.
Available values:
null (default) - auto-detect strict mode from the code. If the code has explicit 'use strict' directive, ES module syntax, or class methods, it's treated as strict mode. Otherwise, sloppy mode is assumed.true - force strict mode treatment for all code, even without explicit 'use strict' directive. Use this when your code will run in strict mode context (e.g., in ES modules, bundlers, or modern frameworks).false - only explicit strict mode indicators ('use strict', ES modules, class methods) are treated as strict. Parent scope inheritance still applies per JS spec.parseHtmlType: boolean Default: false
Enables obfuscation of JavaScript within HTML <script> tags.
When enabled, the obfuscator will:
<!DOCTYPE, <html>, <head>, <body>, or <script> tags)<script> tags marked with the data-javascript-obfuscator attributeImportant: Only scripts with the data-javascript-obfuscator attribute are obfuscated. Each marked script is obfuscated individually and independently. This means:
var declarations or explicit globalThis assignments)Obfuscated (must have data-javascript-obfuscator attribute):
<script data-javascript-obfuscator> - regular scripts<script type="text/javascript" data-javascript-obfuscator> - explicitly typed scriptsid, class, other data-*, etc.)Skipped (left unchanged):
data-javascript-obfuscator attribute<script type="module"> - ES modules (even with the attribute)<script src="..."> - external scripts (even with the attribute)Note: Source maps are not generated when parseHtml is enabled, as they would not map correctly to the HTML output.
Example:
// input
const html = `<!DOCTYPE html>
<html>
<body>
<!-- This script will NOT be obfuscated -->
<script>
var helper = 'utility';
</script>
<!-- This script WILL be obfuscated -->
<script data-javascript-obfuscator>
var greeting = 'Hello World';
console.log(greeting);
</script>
</body>
</html>`;
JavaScriptObfuscator.obfuscate(html, {
parseHtml: true,
stringArray: true
});
// output: HTML with only the marked script obfuscated
es3, es5, es2015, es2016, es2017, es2018, es2019 and partially es2020
README.md but it's not working!The README on the master branch might not match that of the latest stable release.
Try to run npm link javascript-obfuscator command or install it globally with npm i -g javascript-obfuscator
No. JSX support isn't planned.
var, let or const)?See: Kind of variables
null value instead of BigInt number?BigInt obfuscation works correctly only in environments that support BigInt values. See ESTree spec
renameProperties option, and my code broke! What to do?Try renamePropertiesMode: 'safe' option, if it still doesn't work, just disable this option.
Support us with a monthly donation and help us continue our activities. [Become a backer]
Become a sponsor and get your logo on our README on Github with a link to your site.
Copyright (C) 2016-2026 Timofei Kachalov.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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