使用JavaScript创建静态类

///////////javascript静态类的写法//////////////////////////////
//静态类的名称--ChkMaxLen
function ChkMaxLen() {           }
//静态类的变量列表--ChkMaxLen
    ChkMaxLen.maxLength=0;
    ChkMaxLen.element=null;  
//静态类的函数列表--ChkMaxLen
ChkMaxLen.Init=function (varMaxLenth,varID){
    ChkMaxLen.maxLength=varMaxLenth;
    ChkMaxLen.element =document.all[varID];
    ChkMaxLen.element.attachEvent("onkeypress",ChkMaxLen.doKeypress);
    ChkMaxLen.element.attachEvent("onkeydown",ChkMaxLen.doKeydown);
    ChkMaxLen.element.attachEvent("onbeforepaste",ChkMaxLen.doBeforePaste);
    ChkMaxLen.element.attachEvent("onpaste",ChkMaxLen.doPaste);
};

ChkMaxLen.doKeypress=function (){
    if(!isNaN(ChkMaxLen.maxLength)){
        ChkMaxLen.maxLength = parseInt(ChkMaxLen.maxLength);
        var oTR = ChkMaxLen.element.document.selection.createRange();
        if(oTR.text.length >= 1)
         event.returnValue = true;
        else if(ChkMaxLen.element.value.length > ChkMaxLen.maxLength-1)
         event.returnValue = false;
    }
};

ChkMaxLen.doKeydown=function (){
    setTimeout(function(){
        ChkMaxLen.maxLength = parseInt(ChkMaxLen.maxLength);