JavaScript: Responsive Parallax

JavaScript: Responsive Parallax.js

// Parallax

$(document).ready(function(){
    $window = $(window);
    var width = $window.width();
    $(window).bind('resize', function () {
        width = $window.width();
    });
    $(window).scroll(function() {
        // #hero
        var offset = 0;
        var speed;
        if (width > 640) {
            speed = 5;
        }
        if (width > 1024) {
            speed = 5;
        }
        if (width > 1300) {
            speed = -5;
        }
        var calc = ($window.scrollTop() / speed) + offset;
        var results = '50% '+ calc + 'px';

        if (width > 640) {
            $('#hero').css({ backgroundPosition: results });
        }
    });
});