Custom parallax on mouse move

function parallax() {

    var layer = $('.parallax').find('.parallax__layer');

    $(window).on('mousemove', function (e) {
        var mouseX = e.pageX;
        var mouseY = e.pageY;
        var w = (window.innerWidth / 2) - mouseX;
        var h = (window.innerHeight / 2) - mouseY;


        layer.map(function (key, value) {
            var bottomPosition = (window.innerHeight / 2) * (key / 100);
            var widthPosition = w * (key / 100);
            var heightPosition = h * (key / 100);
            $(value).css({
                'bottom' : '-' + bottomPosition + 'px',
                'transform' : 'translate3d(' + widthPosition + 'px, ' + heightPosition + 'px, 0)'
            });
        });

    });

}

var layer = $('.parallax').find('.parallax__layer');
var width = window.innerWidth + 100;

layer.map(function (key, value) {
    $(value).css({
        'width' : width + 'px',
        'margin-left': -(width / 2) + 'px'
    })
});
parallax();