JavaScript技巧1

1:

//让IE支持getElementsByClassName
document.getElementsByClassName = function(){
 var tTagName ="*";
 if(arguments.length > 1){
  tTagName = arguments[1];
 }
 if(arguments.length > 2){
  var pObj = arguments[2]
 }else{
  var pObj = document;
 }
 var objArr = pObj.getElementsByTagName(tTagName);
 var tRObj = new Array();
 for(var i=0; i<objArr.length; i++){
  if(objArr[i].className == arguments[0]){
   tRObj.push(objArr[i]);
  }
 }
 return tRObj;
}

2:一般来说checkbox不能是只读的。为了实现只读功能，使用如下代码
<input type="checkbox" name="test2"/>

//设置checkbox为只读状态
 var v_checkboxList = document.getElementsByName("test");
 for(var i=0; i<v_checkboxList.length; i++) {
  v_checkboxList[i].onclick = function(){return false;};
 }
3:javascript设置一般元素为只读
function setReadonly(){
   var v_input = document.getElementById("userName");
   v_input.style.color = "red";
   v_input.readOnly = true;
   v_input.readOnly = false;
  }