Question

This might be a silly question, but I can’t seem to find a solution…

I just wanted to make a isNullOrWhiteSpace extension (same name as the .NET one), to determine if a string is '', '0', 0, undefined, null. Nothing crazy.

Now doing it with a typical jQuery extension, it seems it is always looking for a jQuery Object to be passed in. But for in my extension, I need it to work with a simple string, but it doesn’t work at all when I do.

$.fn.isNullOrWhiteSpace = function () {
    if (['', '0', 0, undefined, null].indexOf($.trim(this)) > -1) {
        return false;
    }
    return true;
};

'testing'.isNullOrWhiteSpace(); // doesn't work
// Uncaught TypeError: Object has no method 'isNullOrWhiteSpace'

What am I missing here??

— from answers below, turns out it should be simply:

$.isNullOrWhiteSpace, the $.fn. part makes it a jQuery-Object extension as opposed to just a regular extension (like $.isArray(), $.trim() (which I use in my own question… sigh))

Answer 1

If you must hook this to jQuery — and there’s really no reason to beyond namespace economy — you would do this:

$.nullOrWhitespace = function(s) {
  return !s || !(s.replace(/\s*/, '')); // or something like this; just an example
};

Then call it with

if ( $.nullOrWhitespace( yourString ) ) {
  ... whatever ...
}