当我从onsubmit返回false时，为什么我的HTML表单仍然会提交？ [英] Why does my HTML form still submit when I return false from onsubmit?

问题描述

我写了一个简单的脚本来验证登录表单，如下所示：

I wrote a simple script for validating login form as follows:

<script type="text/javascript">
    function validateLoginForm(){
    var idV = document.forms["LoginForm"]["id"].value;
    var pwdV = document.forms["LoginForm"]["pwd"].value;

    if (idV == null || idV == "" || idV.length < 5) {
          alert("user ID must be filled and of more than 4 characters!!");
          id.focus();
          return false;
    }

    if (pwdV == null || pwdV == "" || pwdV.length < 5) {
        alert("Password must be filled and of more than 4 characters!!");
        pwd.focus();
        return false;
    }

    return true;
}
</script>

并将其称为：

<form name="LoginForm" method="POST" onsubmit="return validateLoginForm()" action="Login" >
.
.
.
.
</form>

问题是javaScript在正确设置时发出警报但最终登录 servlet也自动调用，这是一个错误的事情。为什么会发生这种情况？任何解决方案？

The problem is that javaScript gives out the alert as i set correctly but in the end the Login servlet also called automatically, which is a wrong thing..Why this happens? Any solution?

推荐答案

重定向到登录是因为你有js错误。

Redirect to Login happens because you have js error.

你没有定义变量 id 和 psw 。

所以当你尝试 id.focus（）或 psw.focus（） - 你有js错误并返回默认为true

So when you try id.focus() or psw.focus() - you have js error and return true by default

所以添加此代码：

var id = document.forms["LoginForm"]["id"];
var pwd = document.forms["LoginForm"]["pwd"];
var idV = document.forms["LoginForm"]["id"].value;
var pwdV = document.forms["LoginForm"]["pwd"].value;

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