背景位置的负Y值不会改变

Question

CSS

div {
    width: 300px;
    height: 500px;
    background-image: url(http://i.imgur.com/6TbTDVs.jpg);
    background-position: center top;
}

的jQuery

$(window).scroll(function () {
    var scrolledY = $(window).scrollTop();

    var move = (scrolledY*0.2);

    $('div').css('background-position','center -'+move*-1+'px');
});

http://jsfiddle.net/rgbjoy/8GkSg/

Answer 1

您在数字前面联接-并将与-1相乘，所以它试图将位置设置为某个位置像center --6px，这是无效的。

试试这个：

var move = scrolledY * -0.2;
$('div').css('background-position','center '+move+'px');

Demonstration