settimeout_setinterval3.js

来自「源码JAVASCRIPT精粹」· JavaScript 代码 · 共 78 行

addLoadListener(init);

var intervalProcess = setInterval("alert('GOAL!')", 3000);

function init()
{
  var stopGoalLink = document.getElementById("stopGoalLink");
  attachEventListener(stopGoalLink, "click", stopGoal, false);
}

function stopGoal()
{
  clearInterval(intervalProcess);
}

function addLoadListener(fn)
{
  if (typeof window.addEventListener != 'undefined')
  {
    window.addEventListener('load', fn, false);
  }
  else if (typeof document.addEventListener != 'undefined')
  {
    document.addEventListener('load', fn, false);
  }
  else if (typeof window.attachEvent != 'undefined')
  {
    window.attachEvent('onload', fn);
  }
  else
  {
    var oldfn = window.onload;
    if (typeof window.onload != 'function')
    {
      window.onload = fn;
    }
    else
    {
      window.onload = function()
      {
        oldfn();
        fn();
      };
    }
  }
}

function attachEventListener(target, eventType, functionRef, capture)
{
  if (typeof target.addEventListener != "undefined")
  {
    target.addEventListener(eventType, functionRef, capture);
  }
  else if (typeof target.attachEvent != "undefined")
  {
    target.attachEvent("on" + eventType, functionRef);
  }
  else
  {
    eventType = "on" + eventType;

    if (typeof target[eventType] == "function")
    {
      var oldListener = target[eventType];

      target[eventType] = function()
      {
        oldListener();

        return functionRef();
      };
    }
    else
    {
      target[eventType] = functionRef;
    }
  }
}