Question

所以我正在使用这个jquery背景滚动器，基本上我想在同一页面上获得两个以上（以不同的速度运行），我无法弄清楚如何做到这一点。

http://www.devirtuoso.com/2009/07/how-to-build-an-animated-header-in-jquery/

var scrollSpeed = 70;       // Speed in milliseconds
var step = 1;               // How many pixels to move per step
var current = 0;            // The current pixel row
var imageHeight = 4300;     // Background image height
var headerHeight = 300;     // How tall the header is.

//The pixel row where to start a new loop
var restartPosition = -(imageHeight - headerHeight);

function scrollBg(){

    //Go to next pixel row.
    current -= step;

    //If at the end of the image, then go to the top.
    if (current == restartPosition){
        current = 0;
    }

    //Set the CSS of the header.
    $('#header').css("background-position","0 "+current+"px");


}

//Calls the scrolling function repeatedly
var init = setInterval("scrollBg()", scrollSpeed);

我可以在脚本中添加其他css，但我希望其他div的速度不同。

Answer 1

@andy，这是Tom Th的想法得到了解决;即一个js构造函数，您可以从中实例化多个实例：

function bgScroller(options) {
    var settings = {
        containerID: '', //id of the scroller's containing element
        scrollSpeed: 50, //Speed in milliseconds
        step: 1, //How many pixels to move per step
        imageHeight: 0, //Background image height
        headerHeight: 0, //How tall the header is.
        autoStart: true
    };
    if(options) {
        jQuery.extend(settings, options);
    }
    var current = 0, // The current pixel row
        restartPosition = -(settings.imageHeight - settings.headerHeight), //The pixel row where to start a new loop 
        interval = null,
        $container = jQuery('#' + settings.containerID),
        that = {};
    if(!$container.length || !settings.imageHeight || !settings.headerHeight) {
        return false; //nothing will work without these settings so let's not even try
    }
    function setBg() {
        $container.css("background-position", "0 " + current + "px");
    }
    function scrollBg(){
        current -= settings.step;//Go to next pixel row.
        //If at the end of the image, then go to the top.
        if (current <= restartPosition){
            current = 0;
        }
        setBg();
    }
    that.reset = function() {
        that.stop();
        current = 0;
        setBg();
    }
    that.start = function() {
        interval = setInterval(scrollBg, settings.scrollSpeed);
    };
    that.stop = function(){
        clearInterval(interval);
    };
    that.reset();
    if(settings.autoStart) {
        that.start();
    }
    return that;
}

参数作为对象文字“map”的属性传递，覆盖构造函数中的硬编码默认值。对于未包含的任何参数，将使用默认值。以下是几个例子：

var headerScroller = new bgScroller({
    containerID: "header",
    scrollSpeed: 70, //Speed in milliseconds
    imageHeight: 4300, //Background image height
    headerHeight: 300, //How tall the header is.
});
var otherScroller = new bgScroller({
    containerID: "myOtherDiv",
    scrollSpeed: 30, //Speed in milliseconds
    imageHeight: 2800, //Background image height
    headerHeight: 200, //How tall the header is.
});

我已经包含了三种公共方法; .reset()，.start()和.stop()，它们在实例化后对滚动条提供有限的控制。使用方法如下：

headerScroller.stop();
headerScroller.reset();
headerScroller.start();

注意：

工作演示here。
依赖关系：jQuery 1.0或更高版本
.reset()会自动调用.stop()，因此无需事先致电.stop()。
在实例化后没有为更改设置做出规定，但是可以稍微考虑一下。
jQuery插件会类似，但需要花费更多时间来开发（没有什么优势）。

在同一页面上需要多个相同的jQuery效果

1 个答案: