Javascript 只影响一个元素

Question

我不明白，边框只在第一个元素上可见，为什么？

HTML

<div id="theContainer">
    <div id="item">Content 1</div>
    <div id="item">Content 2</div>
</div>​

JavaScript

document.getElementById('item').style.borderTop = '1px solid #0ea2c7';​

JsFiddle:here

Answer 1

您可以使用document.getElementsByClassName

JavaScript

var elements = document.getElementsByClassName('item');
for (i =0; i < ele.length; i++)    {
    elements[i].style.borderTop = '1px solid #000';
}

HTML

<div id="theContainer">
    <div class="item">Content 1</div>
    <div class="item">Content 2</div>
</div>​

CSS

#theContainer {
    height: 100px;
    width: 500px;
    position: relative;
    border: 1px solid #900;
    padding: 10px;
}
.item {
    height: 50px;
    width: 100%;
}
​