Javascript .removeChild & .appendChild 不工作

发布于 2024-11-06 11:28:27 字数 750 浏览 0 评论 0原文

我正在尝试使用一个非常简单的 Javascript 函数来工作，该函数将使用 .removeChild 和 .appendChild 将一张图像更改为另一张图像。我的代码如下：

<html> 
<head> 
<script type="text/javascript" language="javascript"> 
function bannerload(){

var banner = new Image();
banner.src = "IMG/banner.gif";

var loading = new Image();
loading.src = "IMG/loading.gif";

var bannerElement = document.getElementById("BANNER");

bannerElement.removeChild(banner);
bannerElement.appendChild(loading);
}
</script> 
</head> 

<body onload="bannerload()"> 
<div id="BANNER">
<img src="IMG/banner.gif" alt="Banner" />
</div> 
</body> 
</html>

但是，它不起作用。该页面只是加载了banner.gif，并且该图像从未更改为loading.gif。我不明白为什么，请帮忙？！

谢谢！

原文

I'm trying to get a very simple Javascript function to work that will change one image for another using .removeChild and .appendChild. My code is as follows:

<html> 
<head> 
<script type="text/javascript" language="javascript"> 
function bannerload(){

var banner = new Image();
banner.src = "IMG/banner.gif";

var loading = new Image();
loading.src = "IMG/loading.gif";

var bannerElement = document.getElementById("BANNER");

bannerElement.removeChild(banner);
bannerElement.appendChild(loading);
}
</script> 
</head> 

<body onload="bannerload()"> 
<div id="BANNER">
<img src="IMG/banner.gif" alt="Banner" />
</div> 
</body> 
</html>

However, it's not working. The page just loads up with banner.gif and this image is never changed to loading.gif. I can't figure out why, some help pls?!

Thanks!

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世界如花海般美丽 2024-11-13 11:28:27

这不起作用的原因是您正在尝试添加一个子项并删除一个不是子项的子项。

您正尝试从名为 BANNER 的元素中删除名为 BANNER 的子元素。

显然，名为 BANNER 的元素没有名为 Banner 的子元素。您有两种选择，要么为子元素提供 id 并调用“banner.parent.removeChild(banner)”，要么执行以下操作：

示例片段

var bannerElement = document.getElementById("BANNER");
//Banner only has one child.
var child = bannerElement.children[0];

bannerElement.removeChild(child);
bannerElement.appendChild(loading);

The reason this doesn't work is you are trying to add a child and remove a child that isn't a child.

You are trying to remove the child named BANNER from the element named BANNER.

Obviously the element named BANNER doesn't have a child named banner. You have two choices either give the id to the child element and call `banner.parent.removeChild(banner) or the following:

Example snipet

var bannerElement = document.getElementById("BANNER");
//Banner only has one child.
var child = bannerElement.children[0];

bannerElement.removeChild(child);
bannerElement.appendChild(loading);

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奈何桥上唱咆哮 2024-11-13 11:28:27

我认为你的问题是你试图删除bannerElement 中不存在的子元素。

var banner = new Image();
banner.src = "IMG/banner.gif";
...
bannerElement.removeChild(banner);

看看如何制作新图像然后将其删除，即使您尚未附加它？我认为你应该尝试这样的事情：

var banner = document.getElementById('id_banner')
banner.src = 'IMG/banner.gif' // or 'IMG/loading.gif' depending on which one you want
...
<body onload="bannerload()"> 
    <div id="BANNER">
        <img id="id_banner" src="IMG/banner.gif" alt="Banner" />
...

I think your problem is that you're trying to remove a child that doesn't exist in the bannerElement.

var banner = new Image();
banner.src = "IMG/banner.gif";
...
bannerElement.removeChild(banner);

See how you're making a new image and then removing it, even though you didn't append it yet? I think you should try something like this:

var banner = document.getElementById('id_banner')
banner.src = 'IMG/banner.gif' // or 'IMG/loading.gif' depending on which one you want
...
<body onload="bannerload()"> 
    <div id="BANNER">
        <img id="id_banner" src="IMG/banner.gif" alt="Banner" />
...

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