settimeout.ts

(function (global) {
  'use strict';

  if (global.setTimeout) { return; }

  let nextId = 1;
  let tasksById = {};

  function setTimeout(fn: () => void, ms: number) {
    tasksById[nextId] = fn;
    registerSetTimeout(nextId, ms);
    return nextId++;
  }

  function clearTimeout(id: number) {
    delete tasksById[id];
  }

  function runIfPresent(id: number) {
    let task = tasksById[id];
    if (task) {
      try {
        task();
      } finally {
        clearTimeout(id);
      }
    }
  }
  
  function registerSetTimeout(id: number, ms: number) {
    global.runInBackground(() => {
      global.pause(ms);
      runIfPresent(id);
    });
  }

  global.setTimeout = setTimeout;
  global.clearTimeout = clearTimeout;
}(control));