Moving body background

app.js

// single-line solution
$('body').css('background-position', 'center ' + (-window.pageYOffset / 8) + 'px');

// more advanced solution
$('.paralax').each(function() {
        var position = (-window.pageYOffset) + $(this).offset().top

        position = -(position / 8)

        if (position >= ($(this).height() + $(this).height() / 2)) {
            position = 'bottom'
        }
        else if (position < -($(this).height() / 2)) {
            position = 'top'
        }
        else {
            position += 'px'
        }

        console.log(position)

        $(this).css('background-position', 'center ' + position)
    })