表单验证

需要验证的数据：

• 必填项是否填写
• 邮件地址是否合法
• 日期是否合法
• 填写的数据类型是否一致

测试

源代码：

<form action="" method="post" onsubmit="return validate_form(this)">
    Email: <input type="text" name="email" size="30"><br/>
    Usename: <input type="text" name="username" size="30"><br/>
    <input type="submit" value="submit">
</form>
<script>
    function validate_form(thisform){
        with (thisform){
            if(validate_required(email,"邮件必须填写") == false){
                email.focus();
                return false;
            }
            if(validate_email(email,"邮件格式不合法") == false){
                email.focus();
                return false;
            }
            if(validate_required(username,"用户名必须填写") == false){
                username.focus();
                return false;
            }
        }
    }

    function validate_required(field,msg){
        with(field){
            if(value == null || value == ""){
                alert(msg);
                return false;
            }else{
                return true;
            }
        }
    }

    function validate_email(field,msg){
        with(field){
            apos = value.indexOf("@");
            dotpos = value.lastIndexOf(".");
            if(apos < 1 || dotpos < 2){
                alert(msg);
                return false;
            }else{
                return true;
            }
        }
    }
</script>