使用jQuery Validation插件来验证表单

jQuery Validation是一个用于验证表单的jQuery插件，简单易用，已经包含了16种内置的验证规则．Github上也有更多的验证规则可以使用．这都不是重点，重点是你可以轻松的定制自己的规则．

内置规则：

required – Makes the element required.
remote – Requests a resource to check the element for validity.
minlength – Makes the element require a given minimum length.
maxlength – Makes the element require a given maximum length.
rangelength – Makes the element require a given value range.
min – Makes the element require a given minimum.
max – Makes the element require a given maximum.
range – Makes the element require a given value range.
step – Makes the element require a given step.
email – Makes the element require a valid email
url – Makes the element require a valid url
date – Makes the element require a date.
dateISO – Makes the element require an ISO date.
number – Makes the element require a decimal number.
digits – Makes the element require digits only.
equalTo – Requires the element to be the same as another one

内置规则的使用

内置规则的使用非常简单：

首先将该插件的js文件包含进html文件：

1 2	<script src="/static/js/jquery.min.js"></script> <script src="/static/js/jquery.validate.min.js"></script>

然后用jQuery选择需要验证的表单，执行validate()函数即可：

    <script>
    $("#form_id").validate();
    </script>
 ```   

jQuery Validation官网上的例子：

    <!DOCTYPE HTML>
    <html>
    <head>
    <script src="jquery.min.js"></script>
    </head>
    <body>
    <form class="cmxform" id="commentForm" method="get" action="">
    <fieldset>
    <legend>Please provide your name, email address (won't be published) and a comment</legend>
    <p>
    <label for="cname">Name (required, at least 2 characters)</label>
    <input id="cname" name="name" minlength="2" type="text" required>
    </p>
    <p>
    <label for="cemail">E-Mail (required)</label>
    <input id="cemail" type="email" name="email" required>
    </p>
    <p>
    <label for="curl">URL (optional)</label>
    <input id="curl" type="url" name="url">
    </p>
    <p>
    <label for="ccomment">Your comment (required)</label>
    <textarea id="ccomment" name="comment" required></textarea>
    </p>
    <p>
    <input class="submit" type="submit" value="Submit">
    </p>
    </fieldset>
    </form>
    <script>
    $("#commentForm").validate();
    </script>
    </body>
    </html>


jQuery Validation会根据表单设置的type和属性自动为他们分配内置的规则，比如email,url,required等．

运行一下看看：

什么都不输入，直接点提交

输入错误的Email地址，改正后错误提示自动消失

**_添加自定义规则_**

jQuery Validation最吸引人的feature，它可以轻松的加入自定义的规则：

第一步，在js中调用jQuery.validator.addMethod函数来添加规则，例如添加IP格式检查的规则：

    $.validator.addMethod( "ipv4", function( value, element ) {return this.optional( element ) || /^(25[0-5]|2[0-4]\d|[01]?\d\d?)\.(25[0-5]|2[0-4]\d|[01]?\d\d?)\.(25[0-5]|2[0-4]\d|[01]?\d\d?)\.(25[0-5]|2[0-4]\d|[01]?\d\d?)$/i.test( value );}, "Invalid IP v4 address." );　//自定义其他规则只需要替换规则名"ipv4",正则表达式//之间的内容,以及出错后显示的字符串"Invalid IP v4 address."即可．
    

第二步，把规则应用到指定的表单项，即在执行$("#form_id").validate()函数的时候加入rules参数：

    23 $("#ip_form").validate({
    24     rules: {
    25         ip: {
    26             required: true,
    27             ipv4: true,
    28         },
    29         netmask: {
    30             required: true,
    31             ipv4: true,
    32         },
    33         gateway: {
    34             required: true,
    35             ipv4: true,
    36         },
    37     },
    38 }); //其中ip,netmask,gateway为表单项的name属性．required和ipv4是规则名．

1 2	生效后的样子，可以添加如下css来修改错误信息的样式：

    label.error {
        margin-left: 10px;
        padding-left: 5px;
        padding-right: 5px;
        color: #E2303A;
        font-style: italic;
        font: Helvetica Neue, 12px, #E2303A;
        border: 1px solid #F2A9AE;
    }


**_使用json提交数据_**

表单验证通过后，提交动作默认是使用form本身的提交动作，即指定form的action和method属性：

` method="get" action=""`

可以在validate()函数中添加submitHandler参数来指定点击提交后执行的函数，我们可以在该函数中使用$.json来提交数据：

    23 $("#ip_form").validate({
    24     rules: {
    25         ip: {
    26             required: true,
    27             ipv4: true,
    28         },
    29         netmask: {
    30             required: true,
    31             ipv4: true,
    32         },
    33         gateway: {
    34             required: true,
    35             ipv4: true,
    36         },
    37         dns: {
    38             dns: true,
    39         }
    40     },
    41     submitHandler: function(form) {
    42         ip_ok();
    43         $("#ip-conf").modal('hide');
    44     }
    45 });

```