Question

当用户滚动可滚动的div（列表）时，我希望它能够精确滚动列表项的1个高度（22px）。我遇到的问题是，如果我处理$（element）.scroll事件并在其中执行$（element）.scrollTop（previousScrollTop + 22），将触发新的“scroll”事件，并且将递归地再次调用我的处理程序。

请看一下这个例子： http://jsfiddle.net/VAFkk/1/

如何实现一定数量像素的滚动？
我怎么能够更改scrollTop而不触发“scroll”事件？

不胜感激任何建议。使用JQuery 1.9.1。

JavaScript的：

var previousScrollTop = $('.list').scrollTop();

// Bind scroll handler so that it scrolls exactly 22px.
$('.list').scroll(function() {
    console.log('scroll happened');
    var listElement = $(this);
    var currentScrollTop = listElement.scrollTop();

    if (currentScrollTop > previousScrollTop) {
        listElement.scrollTop(previousScrollTop + 22);
    } else if (currentScrollTop < previousScrollTop) {
        listElement.scrollTop(previousScrollTop - 22);
    }

    previousScrollTop = currentScrollTop;
});

HTML：

<div class="list">
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
    <div class="list-item"></div>
</div>

CSS：

.list {
    border: 1px solid red;
    max-height: 88px;
    overflow-y: auto;
}

.list-item {
    border: 1px solid blue;
    height: 20px;
}

Answer 1

(function (step) { // capture variables so you don't pollute
    var prev = $('.list').scrollTop(),
        ignore_scroll = false; // flag
    // declare what we want to do
    function scroll_function(e) {
        var me, cur;
        // if flag true, don't do anything more
        if (ignore_scroll) return;
        // get vars after check (saves needless calls)
        me = $(this),
        cur = me.scrollTop();
        // set flag
        ignore_scroll = true;
        // do stuff
        if (cur > prev) me.scrollTop(prev += step);
        else if (cur < prev) me.scrollTop(prev -= step);
        // unset flag
        ignore_scroll = false;
        /* optional bonus, fix odd ends
        prev = prev - (prev % step)
        */
    }
    // add handler
    $('.list').scroll(scroll_function);
}(22)); // invoke

滚动div一定数量的像素：如何滚动div而不会导致滚动事件

1 个答案: