CHelper.ClrKey

var CHelper={
    ClrKey:function(selector,key){
        $(selector).focus(function(){
            if($.trim($(this).val())==key){$(this).val("");}
            $(this).css("color","#000000");
        });

        $(selector).blur(function(){
            var v=$.trim($(this).val());
            if(v.length<1 || v==key){
                $(this).val(key);
                $(this).css("color","");
            }
        });
    },
    ClrObj:function(selector){
        CHelper.ClrKey(selector,$(selector).val());
    }
}

CHelper.ClrKey("#txtContent","请输入内容");

CHelper.ClrObj("#txtContent");