JavaScript, how to validate if string?

Question

I'm working on a form where my user enters a number between 0-100. If my user puts in 101, it will return with an alert saying that the numbers are invalid. But how do I validate so he doesn't put in something like "asdfasdf" or if it's just empty?

This is my Validate Script:

        function validate() {
        var pct = $('#pct').val();
        if (pct !== "" && (pct > 100 || pct < 0))
            return false;
        else
            return true;
    }

Answer 1

Try this:

function validate() {
   var pct = parseInt($('#pct').val());
   return (pct <= 100) && (pct >= 0);
}

parseInt('not a number') -> NaN Comparison result with NaN is always false. So try represent expression as positive and play with it.