Preload images in a semi fancy way

preload.js

$( function () {
	$( '[data-image]' ).each( function ( i, elem ) {
		var $elem = $( elem ),
		url = $elem.attr( 'data-image' );
		if ( url == null || url.length <= 0 ) { return; }

		if ( !Modernizr.svg ) {
			url = url.replace( /\.svg$/, '.png' );
		}

		$elem.addClass( 'image-loading' );
		$( '<img/>' ).attr( 'src', url ).load( function () {
			$( this ).remove();
			$elem.css( 'background-image', 'url(' + url + ')' );
			$elem.removeClass( 'image-loading' );
			$elem.addClass( 'image-ready' );
		} );
	} );

} );