Question

This sounds like it would be a fairly common issue, but I’ve searched a lot and can’t find anything that works. I’m using the jquery validate plug-in to validate form input. There’s a field which needs to accept only negative numbers (can be whole integers or decimals but must be less than zero).

I’ve tried doing something like this:

    $.validator.addClassRules("negativeNumber", { range: [-1000000000, 0] });

…which works okay, but the validation error is horrible (“Please enter a number between -1000000000 and 0”) – I’d like it to just say “Please enter a negative number”.

Could anyone point me in the direction of a regex that only allows negative numbers?

Many thanks folks…

Answer 1

Instead of a regex, you can add a custom validation method, which I believe is easier to read.

$.validator.addMethod('negativeNumber',
    function (value) { 
        return Number(value) < 0;
    }, 'Enter a negative number');