transform.js

(function () {

  function errMsg(errCode, msg) {
    return (msg || "") + " (SystemJS Error#" + errCode + " " + "https://github.com/systemjs/systemjs/blob/main/docs/errors.md#" + errCode + ")";
  }

  /*
   * Support for a "transform" loader interface
   *
   * Note: This extra is deprecated and will be removed in the next major.
   */
  (function (global) {
    var systemJSPrototype = global.System.constructor.prototype;

    var instantiate = systemJSPrototype.instantiate;
    systemJSPrototype.instantiate = function (url, parent, meta) {
      if (url.slice(-5) === '.wasm')
        return instantiate.call(this, url, parent, meta);

      var loader = this;
      return fetch(url, { credentials: 'same-origin' })
      .then(function (res) {
        if (!res.ok)
          throw Error(errMsg(7, 'Fetch error: ' + res.status + ' ' + res.statusText + (parent ? ' loading from ' + parent : '')));
        return res.text();
      })
      .then(function (source) {
        return loader.transform.call(this, url, source);
      })
      .then(function (source) {
        (0, eval)(source + '\n//# sourceURL=' + url);
        return loader.getRegister(url);
      });
    };

    // Hookable transform function!
    systemJSPrototype.transform = function (_id, source) {
      return source;
    };
  })(typeof self !== 'undefined' ? self : global);

})();