README-en_US.md

eval5

中文 | English

A JavaScript interpreter written in TypeScript, Supports full ES5 syntax.

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 = Interpreter.global, options?: Options )

---

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