jquery validate 例子延伸--如何使用classname而不是name来验证

<form id="myform">
    <input type="text" name="field_1" class="num"/>
    <br/>
    <input type="text" name="field_2" class="num"/>
    <br/>
    <input type="text" name="field_3" class="num"/>
    <br/>
    <input type="submit" />
</form>
<a id="docs" href="http://docs.jquery.com/Plugins/Validation" target="_blank">Validation Documentation</a>

$(document).ready(function () {

    $('#myform').validate({ // initialize the plugin
        submitHandler: function (form) { // for demo
            alert('valid form submitted'); // for demo
            return false; // for demo
        }
    });
    
    $('.num').each(function() {
        $(this).rules('add', {
            required: true,
            number: true,
            messages: {
                required:  "your custom required message",
                number:  "your custom number message"
            }
        });
    });

});