如何在 javascript 函数中使用 getElementsByClassName? [英] How to use getElementsByClassName in javascript-function?

问题描述

我不知道如何在 JavaScript 中使用多个 ID.单个 ID 和 getElementById 没有问题，但是一旦我将 ID 更改为类并尝试使用 getElementsByClassName，该函数就会停止工作.我已经阅读了大约 100 篇关于该主题的帖子；仍然没有找到答案，所以我希望这里有人知道如何使 getElementsByClassName 工作.

I can't figure out how to use multiple IDs in JavaScript. No problem with single ID and getElementById, but as soon as I change IDs to class and try using getElementsByClassName the function stops working. I've read about a 100 post about the topic; still haven't found the answer, so I hope someone here knows how to make getElementsByClassName work.

这是我用于测试的一些简单代码:

Here's some simple code that I have used for testing:

function change(){
    document.getElementById('box_one').style.backgroundColor = "blue";
}

function change_boxes(){
    document.getElementsByClassName ('boxes').style.backgroundColor = "green";
}

   
<input name="" type="button" onClick="change(document.getElementById('box_one')); change_boxes(document.getElementsByClassName('boxes'))" value="Click" />   

<div id="box_one"></div>
<div class="boxes" ></div>
<div class="boxes" ></div>

推荐答案

getElementsByClassName() 返回一个 nodeList HTMLCollection*.您试图直接对结果进行操作；您需要遍历结果.

getElementsByClassName() returns a nodeList HTMLCollection*. You are trying to operate directly on the result; you need to iterate through the results.

function change_boxes() {
    var boxes = document.getElementsByClassName('boxes'),
        i = boxes.length;

    while(i--) {
        boxes[i].style.backgroundColor = "green";
    }
}

<小时>

* 更新以反映界面的变化

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