jquery animate动画opacity问题

串行动画中的animate opacity属性，使用时无法控制其完成状态

by weiming le

HTML

<button>go</button>
<p>快速点击go按钮，会出现所有的box都消失。但这并不符合我们的预期，因为每次的点击，我们只会让一个盒子显示，其它都隐藏。</p>
<div class="test">
    <div class="box1 box">
         <h1>lalalalalla</h1>

    </div>
    <div class="box2 box">
         <h1>hahahahahha</h1>

    </div>
    <div class="box3 box">
         <h1>xixixixixixi</h1>

    </div>
    <div class="box4 box">
         <h1>dididididdid</h1>

    </div>
</div>

CSS

* {
    margin: 0;
    padding: 0;
}
body {
    font: 12px/1.5 arail;
}
ul {
    list-style: none;
}
button {
    height: 2em;
    font-size: 14px;
    width: 4em;
    background: orange;
    color: #fff;
    border-radius: 3px;
    cursor: pointer;
    margin-bottom: 10px;
    border: 1px solid #eee;
}
.box {
    position: absolute;
    border: 1px solid orange;
    height: 40px;
    line-height: 40px;
    width: 160px;
    background: #eee;
    text-align: center;
}
.box2 {
    top: 120px;
}
.box3 {
    top: 200px;
}
.box4 {
    top: 280px;
}

JavaScript

$(function () {
    var animateFlag = true;
    var clickCount = 1;
    var boxNumber = clickCount % 4;
    $('button').on('click', function () {
        if (animateFlag) {
            animateFlag = false;
            clickCount++;
            $('.box' + boxNumber).animate({
                opacity: 'show'
            }, 300, function () {
                $('.box' + boxNumber).siblings().animate({
                    opacity: 'hide'
                }, function () {
                    animateFlag = true;
                    boxNumber = clickCount % 4;
                    if (!boxNumber) {
                        boxNumber = 4;
                        clickCount = 0;
                    }
                });
            });
        }
    });
});