jQuery Validate 1.81

HTML

<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.8.1/jquery.validate.min.js"></script>
<form id="test">
    <input id="field" class="required fraction" type="text" name="field" />
    <input type="submit" />
</form>

JavaScript

var $validator = $("#test").validate();


$.validator.addMethod("fraction", function (value, element, param) {
    var fracExp = new RegExp("(?:-(?!0))?\d+(?:(?: \d+)?/\d+)?");
    return fracExp.test(value);
}, "Please enter a valid fraction");


$.validator.addClassRules("fraction", {
    fraction: true
});