web_or_worker_shell_read.js

/**
 * @license
 * Copyright 2019 The Emscripten Authors
 * SPDX-License-Identifier: MIT
 */

#if ENVIRONMENT_MAY_BE_WORKER
  if (ENVIRONMENT_IS_WORKER) {
    readBinary = (url) => {
      var xhr = new XMLHttpRequest();
      xhr.open('GET', url, false);
      xhr.responseType = 'arraybuffer';
      xhr.send(null);
      return new Uint8Array(/** @type{!ArrayBuffer} */(xhr.response));
    };
  }
#endif

  readAsync = (url) => {
#if ENVIRONMENT_MAY_BE_WEBVIEW
    // Fetch has some additional restrictions over XHR, like it can't be used on a file:// url.
    // See https://github.com/github/fetch/pull/92#issuecomment-140665932
    // Cordova or Electron apps are typically loaded from a file:// url.
    // So use XHR on webview if URL is a file URL.
    if (isFileURI(url)) {
      return new Promise((resolve, reject) => {
        var xhr = new XMLHttpRequest();
        xhr.open('GET', url, true);
        xhr.responseType = 'arraybuffer';
        xhr.onload = () => {
          if (xhr.status == 200 || (xhr.status == 0 && xhr.response)) { // file URLs can return 0
            resolve(xhr.response);
            return;
          }
          reject(xhr.status);
        };
        xhr.onerror = reject;
        xhr.send(null);
      });
    }
#elif ASSERTIONS
    assert(!isFileURI(url), "readAsync does not work with file:// URLs");
#endif
    return fetch(url, {{{ makeModuleReceiveExpr('fetchSettings', "{ credentials: 'same-origin' }") }}})
      .then((response) => {
        if (response.ok) {
          return response.arrayBuffer();
        }
        return Promise.reject(new Error(response.status + ' : ' + response.url));
      })
  };