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

Core libraries of TAO

define(function () { 'use strict';

    /**
     * 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 ;
     */
    /**
     * @author Jean-Sébastien Conan <jean-sebastien.conan@vesperiagroup.com>
     */

    /**
     * Gets a timer
     * @param {Object|Boolean} config - The init config
     * @param {Boolean} [config.autoStart] - Auto start the timer (default: true)
     * @param {Number} [config.startDuration] - Initial duration (default: 0)
     * @returns {timer}
     */
    function timerFactory(config) {
      var initConfig = config || {};
      var begin = now();
      var last = begin;
      var duration = initConfig.startDuration || 0;
      var state = {};
      var disableAutoStart = false === initConfig.autoStart;

      /**
       * The timer instance
       * @type {timer}
       */
      var timer = {
        /**
         * Starts the timer
         * @param {Number} [startDuration] - Initial duration (default: 0)
         * @returns {timer}
         */
        start: function start(startDuration) {
          begin = now();
          last = begin;
          duration = startDuration || 0;
          state.running = true;
          state.started = true;
          return this;
        },
        /**
         * Gets the time elapsed since the last tick
         * @returns {number}
         */
        tick: function tick() {
          var timestamp = now();
          var elapsed;
          if (state.running) {
            elapsed = timestamp - last;
            last = timestamp;
          }
          return elapsed;
        },
        /**
         * Pause the timer
         * @returns {timer}
         */
        pause: function pause() {
          if (state.running) {
            duration += now() - begin;
            state.running = false;
          }
          return this;
        },
        /**
         * Resume the timer
         * @returns {timer}
         */
        resume: function resume() {
          if (!state.running) {
            begin = now();
            last = begin;
            state.started = true;
            state.running = true;
          }
          return this;
        },
        /**
         * Stops the timer
         * @returns {timer}
         */
        stop: function stop() {
          if (state.running) {
            duration += now() - begin;
          }
          state.running = false;
          state.started = false;
          return this;
        },
        /**
         * Gets the time elapsed since the last start.
         * If the timer is stopped, gets the total duration between start and stop.
         * @returns {number}
         */
        getDuration: function getDuration() {
          if (state.running) {
            return duration + (now() - begin);
          }
          return duration;
        },
        /**
         * Checks if the timer is in a particular state
         * @param {String} stateName
         * @returns {Boolean}
         */
        is: function is(stateName) {
          return !!state[stateName];
        },
        /**
         * Add time to the timer
         * @param {Number} time
         * @returns {timer}
         */
        add: function add(time) {
          time = parseFloat(time);
          duration += time;
          last -= time;
          return this;
        },
        /**
         * Remove time from the timer
         * @param {Number} time
         * @returns {timer}
         */
        sub: function sub(time) {
          time = parseFloat(time);
          duration -= time;
          last += time;
          return this;
        }
      };

      /**
       * Simple wrapper around the time provider
       * @returns {Number}
       */
      function now() {
        return window.performance.now();
      }
      if (!disableAutoStart) {
        timer.start(initConfig.startDuration);
      }
      return timer;
    }

    return timerFactory;

});