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我正在制作一个网页，它使用带有一点视差滚动的图层。我有这个工作。然后我不知道发生了什么，因为它停止工作。任何帮助，将不胜感激。这是代码。

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title> 'Test'</title>
    <link rel="stylesheet" href="/css/21.css">
    <script src="/js/21.js" type="text/javascript"></script>
</head>
<body>
    <div id="parallax"></div>
    <script>
        document.addEventListener("DOMContentLoaded", function(){ initParallax(); });
    </script>
</body>
</html>

和 Javascript

var initParallax = function() {

    // Setup variables
    var el = document.getElementById("parallax");
    var layerDistanceToHorizon = [50, 30, 10, 5];
    var horizonDistance = 200;

    // Simplified ways to get the background size (we should use all of them in our calculation)
    var style = window.getComputedStyle(el, null);
    var backgroundSize = style.getPropertyValue("background-size")
        .split(",")[0].split(" ")
        .map(function(x) {
            return parseInt(x)
        });
    var backgroundOffset = style.getPropertyValue("background-position")
        .split(",")[0].split(" ")
        .map(function(x) {
            return parseInt(x)
        });

    //  The original viewer offset (set to the center of the element here.)
    var viewerOffset = [el.offsetWidth / 2, el.offsetHeight / 2];

    // Determine the offsets of the element for the mouse-cursor 
    // coordinates
    elOffsets = Utility.getPosition(el);

    // Function : Calculate all new offsets according to the viewer x/y
    var calculateOffsets = function(x, y) {
        var xTan = -1 * x / horizonDistance;
        var yTan = -1 * y / horizonDistance;
        return layerDistanceToHorizon.map(function(value) {
            return [value * xTan, value * yTan];
        });
    };

    // Function : Actually move the viewer
    var moveViewer = function(x, y) {
        var offsets = calculateOffsets(x, y);

        el.style.backgroundPosition = offsets.map(function(off) {
            var x = backgroundOffset[0] - off[0];
            var y = backgroundOffset[1] - off[1];
            return x + "px " + y + "px";
        }).join(", ");
    };

    //  Add the mouse-move event
    document.addEventListener("mousemove", function(e) {
        var mouse = getEventMousePosition(e);
        moveViewer(mouse[0] - (elOffsets[0] + viewerOffset[0]), mouse[1] - (elOffsets[1] + viewerOffset[1]));
    });
};


// Get the mouse coordinates from an event
var getEventMousePosition = function(e) {
    var x = 0;
    var y = 0;

    if (!e) var e = window.event;
    if (e.pageX || e.pageY) {
        x = e.pageX;
        y = e.pageY;
    } else if (e.clientX || e.clientY) {
        x = e.clientX + document.body.scrollLeft;
        y = e.clientY + document.body.scrollTop;
    }
    return [x, y];
}
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