Jquery validation - allow number without the leading zero?

Question

I'm using jquery validation (http://docs.jquery.com/Plugins/Validation) like so:

    var $__field = $("#selector");  
    if ($__field.is(":visible")) {  
        $__field.rules('add', { required: true });
        $__field.rules('add', { number: true });
    } 

If the user enters a number without a leading zero, eg .5 then jquery validation says "Please enter a valid number."

How can I change the validation to allow number entry without requiring the leading zero?

Answer 1

The problem is with the regular expression used for numbers. Looking at the latest version, lines 1021-1023, we've got:

number: function(value, element) {
    return this.optional(element) || /^-?(?:\d+|\d{1,3}(?:,\d{3})+)(?:\.\d+)?$/.test(value);
},

The problem is that this first chunk, which looks for leading negative sign and numbers, either individual or in groups of three separated by commas, is not optional:

(?:\d+|\d{1,3}(?:,\d{3})+)

Tacking a ? on the end will make it optional:

(?:\d+|\d{1,3}(?:,\d{3})+)?

With this update, you can either modify your local copy of the plugin, changing the regular expression to the modified version, or add a new validation method to your javascript:

jQuery.validator.addMethod("numeric", function(value, element) {
    return this.optional(element) || /^-?(?:\d+|\d{1,3}(?:,\d{3})+)?(?:\.\d+)?$/.test(value);
}, "Please enter a valid number.");

On any page with this addMethod call, you can now use numeric to do a number validation that doesn't require a leading zero.