jquery - 具有视差的背景图像

Question

所以我需要网站的一部分与背景图像有视差。问题是代码从网站开始计算视差(这是一个长的向下滚动类型的网站)，当我到达提到的部分时，背景已经太高了。代码中是否需要某种“延迟”，以便在滚动 X 像素后开始出现视差？这里的代码:

JQUERY:

$(document).ready(function() {
    // Cache the Window object
    $window = $(window);

    $('section[data-type="background"]').each(function() {
        var $bgobj = $(this); // assigning the object

        $(window).scroll(function() {

            // Scroll the background at var speed
            // the yPos is a negative value because we're scrolling it UP!                              
            var yPos = -($window.scrollTop() / $bgobj.data('speed'));

            // Put together our final background position
            var coords = '50% ' + yPos + 'px';

            // Move the background
            $bgobj.css({
                backgroundPosition: coords
            });
        }); // window scroll Ends
    });
});

HTML:

<section id="background" data-type="background" data-speed="5">
    <div class="container">
        <div class="shadow-block"><img src="images/shadow-b.png" alt="" class="scale-with-grid"/></div>
            <div class="quote two-thirds column" >  
            </div>
            </div>
</section>

CSS:

#background {
    background: url(../images/big-bg.jpg)no-repeat center center;
    background-size:cover;
    width: 100%;
    height:500px;
    padding: 40px 0;
    overflow: hidden;
    position: relative;
}

Answer 1

你能不能不要这样？

var Top = $(document).scrollTop();
    if(Top < 200){ 
    //Then do the parallax stuff...
}