如何使动画一一播放? [英] How can I make the animations be run one by one?

问题描述

HTML代码:

<ul>
    <li>a</li>
    <li>b</li>
    <li>c</li>
    <li>d</li>
    <li>e</li>
</ul>

js代码:

<script type="text/javascript">
$(document).ready(function() {
    var lis = $("li");
    for (var i = 0; i < lis.length; i++) {
        $(lis[i]).animate({opacity: 0}, 1000);
    }
});
</script>

我只是发现lis会一起消失.我该怎么办，它们会一一消失?

I just find that the lis will disappear together. How can I do that they will disappear one by one?

推荐答案

对不起，您参加晚了.

Sorry for joining the party late.

当计时器阻塞并依赖计时器的准确性时，现有的答案会出现问题，而且它们需要实际的延迟.

The existing answers have issues when a timer blocks and rely on the accuracy of timers, moreover they require an actual delay.

jQuery实际上提供了一种通用的方式来按顺序执行带有诺言的动画:

jQuery actually provides a generic way to perform animations sequentially with promises:

$(document).ready(function() {
    var lis = $("li");
    var queue = $.Deferred().resolve(); // create an empty queue
    lis.get().forEach(function(li){
        queue = queue.then(function(){
           return $(li).animate({opacity: 0}, 1000).promise();
        })
    });
});

小提琴

请注意，即使您为它们分配了不同的动画持续时间或不同的动画，这也将起作用，queue中的结果将在最后一个动画结束时包含一个钩子.这也支持聚合(等待所有诺言并行完成)和更多.

Note that this will work even if you assign them different animation durations or different animations, the result in queue will contain a hook on when the last animation finished. This also supports aggregations (waiting for all promises to finish in parallel) and more.

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