<input id="txt" onblur="err.style.display=this.value!='OK'?'':'none'" value="请输入OK"/><span id='err' style="display:none">错误</span>

解决方案 »

  1.   

    <html><head>
    <meta http-equiv="Content-Type" content="text/html; charset=gb2312">
    <title>new page</title>
    <script>
    function check(){
    if(txt1.value!="ACEBD"){
    span1.innerText="验证码不正确!";
    }else{
    span1.innerText="";
    }
    }
    function doSubmit(){
    check();
    if(txt2.value==""){
    span2.innerText="姓名不能为空!";
    }else{
    span2.innerText="";
    }
    }
    </script>
    </head>
    <body>
    <span>ACEBD</span>
    <br>
    <span>验证码:</span><input type=text id=txt1 name=txt1 value="" onblur="check()"><span id=span1 name=span1 color=red></span>
    <br>
    <span>姓名:</span><input type=text id=txt2 name=txt2 value=""><span id=span2 name=span2 color=red></span>
    <br>
    <input type=button value="提交" onclick="doSubmit()">
    </body>
    </html>
      

  2.   

    function checkName(name){
       var errMsg="姓名不能为空";
       if(name.length==0)
       {
           $("nameMsg").innerText=errMsg;
           return errMsg;
       }
       else
       {
           return "";
       }
    }function checkForm(form){
       var Error;
       var isComplete=true;
       Error+=checkName(form.name.value)+"\n";
       Error+=checkPwd(form.pwd.value)+"\n";
       ....
       if(Error.length>0){
           alert(Error);
           isComplete=false;
       }
       return isComplete;
    }
      

  3.   

    http://hi.baidu.com/lael80/blog/item/94da23c766c12edfd0006072.html
    Validator.js //JS万能验证超强版,增加了好多种使用模式,具体请看代码
      

  4.   


    可以参考JK的Validation: 
    将Element与验证的js分离开,通过element属性来控制验证,给程序员带来尽量多的方便温和警告验证: 
    JKHtml\JKValidation\JKValidationDemo-SoftAlertWhenBlur.htm     
    http://download.csdn.net/source/276201