eval5

eval5

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A JavaScript interpreter written in TypeScript.

Support JavaScript running environment such as browser, node.js, WeChat Mini Program, etc

Try it out

Examples

You may not need it unless

• Need to execute code in the browser with a sandbox environment
• Controlling execution time
• JavaScript runtime environment that does not support eval and Function. for example: WeChat Mini Program demo
• Be interested or Be curious

ECMAScript version supported

ES5

Install

npm install --save eval5

Usage

import { Interpreter } from "eval5";

const interpreter = new Interpreter(window, {
	timeout: 1000,
});

let result;

try {
	result = interpreter.evaluate("1+1");
	console.log(result);

	interpreter.evaluate("var a=100");
	interpreter.evaluate("var b=200");
	result = interpreter.evaluate("a+b");

	console.log(result);
} catch (e) {
	console.log(e);
}

Options

interface Options {
	// default: 0 not limited
	timeout?: number;
	// readonly
	rootContext?: {} | null;
	globalContextInFunction?: any;
}

Example

import { Interpreter } from "eval5";

const ctx = {};
const interpreter = new Interpreter(ctx, {
    rootContext: window,
	timeout: 1000,
});

interpreter.evaluate(`
    a = 100;
    console.log(a); // 100
`);

window.a;//undefined

Interpreter

version

current version

global

default: {}

global context

Interpreter.global = window;
const interpreter = new Interpreter();
interpreter.evaluate('alert("hello eval5")');

globalContextInFunction

default: undefined

eval5 does not support use strict mode, but the default value of this in function calls is undefined, you can set this property as the default.

import { Interpreter } from "Interpreter";

const ctx = {};
const interpreter = new Interpreter(ctx);
interpreter.evaluate(`
this; // ctx
function func(){
    return this; // undefined
}
func();
`);

import { Interpreter } from "Interpreter";

Interpreter.globalContextInFunction = window;
const ctx = {};
const interpreter = new Interpreter(ctx);
interpreter.evaluate(`
this; // ctx
function func(){
    return this; // window
}
func();
`);

Let's take a look at the following example

Note: Illegal invocation

that's why globalContextInFunction is set to undefined

import { Interpreter } from "Interpreter";

Interpreter.globalContextInFunction = {};

const ctx = {alert: alert};

const interpreter = new Interpreter(ctx);

interpreter.evaluate(`
// alert.call({}, 'Hello eval5')
// Illegal invocation
alert('Hello eval5');
`);

constructor(context?: {}: options: Options = Interpreter.global)

---

Instance methods

evaluate(code: string): any

executes string code and returns the value of the last expression

import { Interpreter } from "Interpreter";

const interpreter = new Interpreter(window);

const result = interpreter.evaluate(`
var a = 100;
var b = 200;

a+b;

`);

console.log(result); // 300

appendCode(code: string): any

alias of evaluate

getExecutionTime(): number

get the last execution time

setExecTimeout(timeout: number = 0): void

set the timeout for each execution

getOptions(): Readonly<Options>

get interpreter options

evaluate(code: string, ctx?: {}, options?: Options)

executes string code and returns the value of the last expression

note: a new interpreter is created with every execution

import { evaluate } from "eval5";

evaluate(
	`
var a = 100;
var b = 100;
console.log(a+b);
`,
	{ console: console }
); // 200

evaluate(`
    a;
`); // a is not defined

Function

use Interpreter.global as the default context, Interpreter.globalContextInFunction also

import { Function } from "eval5";

const func = new Function("a", "b", "return a+b;");
console.log(func(100, 200)); // 300

vm

see vm

• vm.createContext
• vm.compileFunction
• vm.runInContext
• vm.runInNewContext
• vm.Script

License

MIT

Related

• evaljs
• closure-interpreter