previous兄弟不工作 [英] previousSibling not working

问题描述

我想通过选择第二个< p> 并使用 previousSibling 属性来定位div中的第一个< p> ，但是它不起作用.

I want to target the first <p> inside the div by selecting the second <p> and using previousSibling property but it is not working.

<div id="par">
<p id="p1">test</p>
<p id="p2">test</p>
</div>


document.getElementById('p2').previousSibling.className = 'red';

好的，它可以在除IE8之外的所有浏览器上运行，但我也希望它也可以在IE8中运行，我尝试了以下条件，但没有任何作用:

OK it works on all browsers except IE8 but I want it to work in IE8 as well, I tried the following conditional but to no effect:

var c = document.getElementById('p2').previousElementSibling.className = 'red';

if (c == undefined) {

    c = document.getElementById('p2').previousSibling.className = 'red';
}

除了IE8之外，它仍然可以在任何地方使用.如何更改IE8的上述条件?

It still works everywhere but IE8. How can I change the above conditional for IE8?

设法使它也可以在IE8中工作:

Managed to get it to work in IE8 as well:

var c = document.getElementById('p2');

if (c.previousElementSibling) {

    c.previousElementSibling.className = 'red';

} else {

    c.previousSibling.className = 'red';

}

推荐答案

您需要使用 previousElementSibling 获取上一个Element节点.

You need to use previousElementSibling to get the previous Element node.

document.getElementById('p2').previousElementSibling.className = 'red';

http://jsfiddle.net/b6Bh8/

注意:根据上面的MDN链接，这在IE< = 8上不起作用.您可能需要遍历 previousSibling ，直到找到一个Element节点.

Note: This does not work on IE <= 8 according to MDN link above. You would probably need to loop through previousSibling until you find an Element node.

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