esper.js

Esper.js

A javascript self-interpreter with a focus on sandboxed execution and runtime introspection.

Demo | Run Tests

Usage

At the most basic level, esper's eval function can be used as a safe replacement for the native eval function.

var four = esper.eval('2+2');

More functionality is available via an Engine object.

var engine = esper({
	
});

engine.addGlobal('two', 2);
engine.load('2+two');
var result = engine.runSync();
result.toNative() === 4;

Options

The esper() function takes an options object as it only parameter.

strict

Type: boolean Default: false

If true, force all code to be run in strict mode.

foreignObjectMode

Type: string Default: enum

addInternalStack

Type: boolean Default: false

If true, the interpreter's internal stack will be added to the stack trace of exceptions.

executionLimit

Type: Integer Default: Infinity

The number of AST nodes methods like .runSync() will evaluate before giving up. Set this to prevent infinite loops.

exposeEsperGlobal

Type: boolean Default: true

Creates a global named Esper inside the interpreter with introspection and metaprogramming functions.

Building

Esper utilizes the webpack build system to create a single file suitable for use in the browser.

--profile=<profile>

Profile	Use
web	The default profile. Creates an single ES5 compatible file with self contained regenerator-runtime and es6 polyfills.
modern	Creates an single ES6 compatible file. More performance than web, but requires a modern browser.
nashorn	Crates a single file targeting the Java Nashorn engine. Uses Nashorn's parser instead of embedded esprima.

--test

Creates a test builds that embeds the unit tests. Including this file in a <script> tag will take over the page and display the test output in real time.

--min

Minify the resulting build using UglifyJS.

Contributing

If you'd like to contribute, please sign the CodeCombat contributor license agreement so we can accept your pull requests.

Checklist for contributing:

• All tests pass. npm run test
• No code style problems. npm run style
• Code coverage increased. npm run cover
• webpack --test build passes test in browser.

License

The MIT License