在表单提交前进行验证的几种方式

1在button的submit事件时判断

<button type="submit">提交</button>  

("#form").bind("submit",function(){
    var txt_firstname = $.trim($("#firstname").attr("value"));

    var isSuccess = 1;//默认验证通过
    if(txt_firstname.length == 0){
        $("#firstnameLabel").text("firstname不能为空！")
        $("#firstnameLabel").css({"color":"red"});
        isSuccess = 0;  //验证不通过，修改isSuccess
   }
    if(isSuccess == 0){
        return false;//最后未通过，不提交
    }
})

2 在form的onsubmit判断

<form id="form" method="post" action="/DealWithForm/" onsubmit="return check()">

function check(){
    var txt_firstname = $.trim($("#firstname").attr("value"));  

    var isSuccess = 1;
    if(txt_firstname.length == 0)
    {
        $("#firstnameLabel").text("firstname不能为空！")
        $("#firstnameLabel").css({"color":"red"});
        isSuccess = 0;
    }  

    if(isSuccess == 0){
        return false;
    }
    return true;
}  

注意：onsubmit=“return false”为不执行提交；onsubmit=“return true”或onsubmit=“return ”都执行提交。

3 去掉submit类型button，直接用普通button.

<button type="button" onclick="checktosubmit()">提交</button>  

function checktosubmit(){
    var txt_firstname = $.trim($("#firstname").attr("value"));

    var isSuccess = 1;
    if(txt_firstname.length == 0)
    {
        $("#firstnameLabel").text("firstname不能为空！")
        $("#firstnameLabel").css({"color":"red"});
        isSuccess = 0;
    }
    if(isSuccess == 1)
    {
        form.submit();
    }
}

原文链接：http://blog.csdn.net/qian_f/article/details/9631691