Respond To for javascript

gistfile1.txt

function respondsTo(respondToSize, callback, undoCallback) {
	if ( typeof respondToSize === 'string' )
	{
		respondToSize = [respondToSize];
	}

	function calculateSize()
	{
		var width = jQuery('body').width();
		var size = 'desktop';

		// Is Tablet
		if ( width <= 960 && width >= 740 )
		{
			size = 'tablet';
		}

		// Is Small Tablet
		else if ( width <= 740 && width >= 600 )
		{
			size = 'small-tablet';
		}

		// Is Wide Mobile
		else if ( width <= 600 && width >= 480 )
		{
			size = 'wide-mobile';
		}

		// Is Mobile
		else if ( width <= 480 )
		{
			size = 'mobile';
		}

		return size;
	}

	jQuery(window).on('resize.breakpoint', function() {
		var size = calculateSize();

		var sizeChanged = window.respondToSize != size;
		var isSize = jQuery.inArray(size, respondToSize) > -1;

		if ( sizeChanged && isSize)
		{
			window.respondToSize = size;

			callback(size);
		}
		else if ( sizeChanged )
		{
			undoCallback(size);
		}
	});
}