@free-side/audioworklet-polyfill/src/realm.js

AudioWorklet polyfill using the legacy ScriptProcessor API.

/**
 * Copyright 2018 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

export function Realm (scope, parentElement) {
  const frame = document.createElement('iframe');
  frame.style.cssText = 'position:absolute;left:0;top:-999px;width:1px;height:1px;';
  parentElement.appendChild(frame);
  const win = frame.contentWindow;
  const doc = win.document;
  let vars = 'var window,$hook';
  for (const i in win) {
    if (!(i in scope) && i !== 'eval') {
      vars += ',';
      vars += i;
    }
  }
  for (const i in scope) {
    vars += ',';
    vars += i;
    vars += '=self.';
    vars += i;
  }
  const script = doc.createElement('script');
  script.appendChild(doc.createTextNode(
    `function $hook(self,console) {"use strict";
        ${vars};return function() {return eval(arguments[0])}}`
  ));
  doc.body.appendChild(script);
  this.exec = win.$hook.call(scope, scope, console);
}