Javascript：如何按类名只获取一个元素？ [英] Javascript: How to get only one element by class name?

问题描述

如何按类名只获取一个DOM元素？我猜测按类名获取元素的语法是getElementsByClassName，但我不确定它将返回多少元素。

How do I get only one DOM element by class name? I am guessing that the syntax of getting elements by class name is getElementsByClassName, but I am not sure how many elements it's going to return.

提前致谢。

推荐答案

document.getElementsByClassName（'className'）总是会返回多个元素，因为从概念上讲类应该应用于多个元素。如果你只希望DOM中的第一个元素与该类，你可以选择返回的数组中的第一个元素。

document.getElementsByClassName('className') would always return multiple elements because conceptually Classes are meant to be applied to multiple elements. If you want only the first element in the DOM with that class, you can select the first element out of the array returned.

var elements = document.getElementsByClassName('className');
var requiredElement = elements[0];

否则，如果你真的只想选择一个元素。然后你需要使用'id'作为概念，它被用作网页中唯一元素的标识符。

Else, if you really want to select only one element. Then you need to use 'id' as conceptually it is used as an identifier for unique elements in a Web Page.

// HTML
<div id="myElement"></div>

// JS
var requiredElement = document.getElementById('myElement');

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