1. 程式人生 > >onload自定義函式的六種寫法

onload自定義函式的六種寫法

第一種方法:

function addfunction(){
 ...
}
<body onload="addfunction()">

第二種方法:

window.onload = addfunction;
function addfunction(){
 ...
}

第三種方法:

window.onload = function(){
 firstFunction();
 secondFunction();
}

第四種方法:

function addLoadEvent(func) {   
  var oldonload = window.onload;   
  if (typeof window.onload != 'function') {   
    window.onload = func;   
  } else {   
    window.onload = function() {   
      oldonload();   
      func();   
    }   
  }   
}
addLoadEvent(addfunction);

第五種方法:

function addEvent(obj,EventName,callBack){//給物件新增事件
  if(obj.addEventListener){
   obj.addEventListener(EventName,callBack,false);
  }else if(obj.attachEvent){//IE
   obj.attachEvent('on'+EventName,callBack);
  }else{
   obj["on"+EventName]=callBack; 
  }
} 
function a(){
 alert("a");
}
 
function b(){
 alert("b");
}
addEvent(window,"load",a);
addEvent(window,"load",b);

第六種方法:

// Please note: this file contains snippets for comparison
// it is not self-contained or ready-to-use code as such

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();
      };
    }
  }
}