@oat-sa/tao-core-sdk/dist/core/requireIfExists.js

Core libraries of TAO

define(['core/promise'], function (Promise) { 'use strict';

    Promise = Promise && Object.prototype.hasOwnProperty.call(Promise, 'default') ? Promise['default'] : Promise;

    /**
     * This program is free software; you can redistribute it and/or
     * modify it under the terms of the GNU General Public License
     * as published by the Free Software Foundation; under version 2
     * of the License (non-upgradable).
     *
     * This program is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     * GNU General Public License for more details.
     *
     * You should have received a copy of the GNU General Public License
     * along with this program; if not, write to the Free Software
     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
     *
     * Copyright (c) 2016-2019 (original work) Open Assessment Technologies SA ;
     */

    /**
     * Requires an optional module. It the module does not exist, an empty resource is provided (null).
     * @param {String} uri - The URI of the module to require
     * @returns {Promise} - Returns a promise that will be resolved either with the loaded resource or an empty resource.
     */
    function requireIfExists(uri) {
      // the promise will always be resolved
      return new Promise(function (resolve) {
        // if a require issue occurs, fallback to an empty resource
        function failed(err) {
          // only catch error related to the required module
          var failedId = err.requireModules && err.requireModules[0];
          if (failedId === uri) {
            // fake the module, then ensure it is truly loaded
            window.requirejs.undef(failedId);
            define(failedId, function () {
              return null;
            });
            window.require([failedId], resolve);
          } else {
            // others errors are not handled
            throw err;
          }
        }

        // require the module with error handling
        window.require([uri], resolve, failed);
      });
    }

    return requireIfExists;

});