ShadowRealm API Polyfill

A implementation of the ShadowRealm API Proposal, a JavaScript sandbox, test with TC39 Test262 cases.

declare class ShadowRealm {
    constructor();
    evaluate(sourceText: string): Primitive | Function;
    importValue(specifier: string, bindingName: string): Promise<Primitive | Function>;
}

Try it now 🎉

Install

npm i -S @haohanyang/shadowrealm-api

Usage

Ponyfill: non-invasive

import ShadowRealm from '@haohanyang/shadowrealm-api'

const realm = new ShadowRealm();

Polyfill: patch up the global object

import '@haohanyang/shadowrealm-api/dist/polyfill'

const realm = new ShadowRealm();

Debugging

Print internal info for debugging

ShadowRealm.__debug = true;

Limitations

1. All code evaluated inside a ShadowRealm runs in strict mode;
2. The ESM statement must not contain redundant comments;

// ❌
import/* */defaultExport from "module-name";
export default/* */'xxx';

// ✅
import defaultExport from "module-name";
export default 'xxx';

3. Exporting variable declarations is not supported;

// ❌
export const obj = {...}, fn = () => {...};

// ✅
const obj = {...}, fn = () => {...};
export { obj, fn };

Compatibility

|IE|Edge|Firefox|Chrome|Safari|Opera| |:-:|:-:|:-:|:-:|:-:|:-:| ||14|29[1][2]|32[1][2]|8[2][3]|19[1][2]| |||41|49|10.1[3]|36| |||||14.1||

Notes:

1. Don't support destructuring assignment in ESM statement;
2. Need fetch polyfill in top window;
3. Need URL polyfill in top window;

Use polyfills:

import "fetch polyfill";
import "URL polyfill";
import "@haohanyang/shadowrealm-api/dist/polyfill";
// Your codes