問題：
I'm trying to get the child span that has a class = 4. Here is an example element:我正在嘗試獲取具有 class = 4 的子跨度。這是一個示例元素：
<div id="test">
<span class="one"></span>
<span class="two"></span>
<span class="three"></span>
<span class="four"></span>
</div>
The tools I have available are JS and YUI2.我可用的工具是 JS 和 YUI2。 I can do something like this:我可以做這樣的事情：
doc = document.getElementById('test');
notes = doc.getElementsByClassName('four');
//or
doc = YAHOO.util.Dom.get('#test');
notes = doc.getElementsByClassName('four');
These do not work in IE.這些在 IE 中不起作用。 I get an error that the object (doc) doesn't support this method or property (getElementsByClassName).我收到一個錯誤，指出對象 (doc) 不支持此方法或屬性 (getElementsByClassName)。 I've tried a few examples of cross browser implementations of getElementsByClassName but I could not get them to work and still got that error.我已經嘗試了幾個 getElementsByClassName 跨瀏覽器實現的例子，但我無法讓它們工作並且仍然得到那個錯誤。
I think what I need is a cross browser getElementsByClassName or I need to use doc.getElementsByTagName('span') and loop through until I find class 4. I'm not sure how to do that though.我想我需要的是跨瀏覽器 getElementsByClassName 或者我需要使用 doc.getElementsByTagName('span') 並循環直到找到第 4 類。不過我不知道該怎麼做。
解決方案：
參考一： https://en.stackoom.com/question/p37x參考二： https://stackoom.com/question/p37x