为什么这个javascript代码只打印第一个列表条目？ [英] Why does this javascript code prints the first list entry only ?
问题描述
我是javascript的初学者。我试图编写一个代码，从文本框中获取用户的输入。我想捕获数组中的输入，所以我在互联网上查找了一种方法。我有一个方法document.getElementsByName（name），它返回具有该名称的所有元素的HTML集合。我编写了一个脚本来使用该功能，但奇怪的是，它只是打印列表中的第一个值。长度函数显示正确的长度，即3，但只打印第一个值。任何帮助，将不胜感激。以下是代码：
I am a beginner in javascript. I was trying to write a code that takes input from the user in textboxes . I wanted to capture the inputs in an array, so i looked up for a method on the internet. I got a method document.getElementsByName("name") that returns an HTML collection of all element with that name. I wrote a script to utilise that function, but strangely, it is just printing only the first value in the list. The length function shows me the correct length, i.e 3 , but only the first value is being printed. Any help would be appreciated. Here is the code:
<html>
<head>
<title>Test</title>
<script type="text/javascript">
function fun(){
var list = document.getElementsByName("array");
document.write(list[0].value+"<br>");
document.write(list[1].value+"<br>");
document.write(list[2].value+"<br>");
}
</script>
</head>
<body>
<input type="text" name="array"><br>
<input type="text" name="array"><br>
<input type="text" name="array"><br>
<input type="button" value="go" onclick="fun()">
</body>
</html>
我尝试过：
我已经尝试逐一打印长度，以及列表中的各个元素。所有这些都有效。但是当我想一次打印所有值时，它只打印第一个值
What I have tried:
I have tried printing the length, as well as individual elements of the list one by one. All of them works. But when i want to print all of the values at once, it just prints the first value
推荐答案
在浏览器中查看错误控制台，你会看到问题：
Check out the error console in your browser, and you'll see the problem:
TypeError: list[1] is undefined
一旦你使用 document.write ，文档的全部内容将替换为您编写的内容。
As soon as you use document.write, the entire contents of the document are replaced with whatever you've written.
注意：当document.write写入文档流时，在已关闭（加载）的文档上调用document.write会自动调用document.open，这将清除文档。
Note: as document.write writes to the document stream, calling document.write on a closed (loaded) document automatically calls document.open, which will clear the document.
清算文件会破坏其中的元素，因此您无法再读取输入值。
您需要在写入文档之前阅读值：
Clearing the document destroys the elements on it, so you can no longer read the value of the inputs.
You'll need to read the values before writing to the document:
function fun(){
var list = document.getElementsByName("array");
var values = [];
for (var i = 0; i < list.length; i++){
values.push(list[i].value);
}
document.write(values.join("<br />"));
document.close();
}
这是工作的Plunker。当你使用document.write时，它会覆盖以前的值。
Working Plunker [ ^ ]
Hepe this help
Here is the working Plunker. When you use document.write , it will overwrite the previous value.
Working Plunker[^]
Hepe this helps
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