Javascript regular expression for negative Numbers with decimal

Question

I want to test for this input: [an optional negative sign] 2 digits [an optional . and an optional digit] like this:

-34 or -34.5333 or

Answer 1

This below simple html code will validate the +ve & -ve numbers of 2 digits plus optional minimum of 1 digit after decimal point.

JS Code:

    function validateNum() {
        var patForReqdFld = /^(\-)?([\d]{2}(?:\.\d{1,})?)$/;
        var value = document.getElementById('txtNum').value;

        if(patForReqdFld.test(value)) {
            alert('Valid Number: ' + value);
        } else {
            alert('Invalid Number: ' + value);
        }
    }

HTML Code:

    Enter Number: