為什么不加speed參數(shù)時(shí)沒有效果，speed不是可選參數(shù)么
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??????? <title>使用fadeTo()方法設(shè)置淡入淡出效果的不透明度</title>
??????? <script src="http://libs.baidu.com/jquery/1.9.0/jquery.js" type="text/javascript"></script>
??????? <link href="style.css" rel="stylesheet" type="text/css" />
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??????? <h3>使用fadeTo()方法設(shè)置淡入淡出效果的不透明度</h3>
??????? <span class="red"></span><span class="orange"></span><span class="blue"></span>
?????? ?
??????? <script type="text/javascript">
??????????? $(function () {
??????????????? $("span").each(function (index) {
??????????????????? switch (index) {
??????????????????????? case 0:
??????????????????????????? $(this).fadeTo(0.2);
??????????????????????????? break;
??????????????????????? case 1:
??????????????????????????? $(this).fadeTo(1000,0.4);
??????????????????????????? break;
??????????????????????? case 2:
??????????????????????????? $(this).fadeTo(1000,0.6);
??????????????????????????? break;
??????????????????? }
??????????????? });
??????????? });
??????? </script>
??? </body>
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2016-06-23
speed可選。規(guī)定元素從當(dāng)前透明度到指定透明度的速度。
可能的值：
毫秒 （比如 1000）"slow""normal""fast"
大概可選的意思是可以在以上值里面選吧，還是要填的。