<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>Makes "field" required having at most 4 characters.</title>
    <link rel="stylesheet" href="https://jqueryvalidation.org/files/demo/site-demos.css">
</head>
<body>
<form id="myform">
    <label for="field">Required, maximum length 4: </label>
    <input type="text" class="left" id="field" name="field">
    <br/>
    <input type="submit" value="Validate!">
</form>
<script src="https://code.jquery.com/jquery-1.11.1.min.js"></script>
<script src="https://cdn.jsdelivr.net/jquery.validation/1.16.0/jquery.validate.min.js"></script>
<script src="https://cdn.jsdelivr.net/jquery.validation/1.16.0/additional-methods.min.js"></script>
<script>
    // just for the demos, avoids form submit
    jQuery.validator.setDefaults({
        debug: true,
        success: "valid"
    });
    $("#myform").validate({
        rules: {
            field: {
                required: true,
                maxlength: 4
            }
        }
    });
</script>
</body>
</html>