在document.getElementsByTagName（input）[0]的末尾添加[0]的效果是什么？ [英] What is the effect of adding [0] at the end of document.getElementsByTagName(input)[0]

问题描述

我看到一些使用 document.getElementsByTagName（input）[0] 结尾处的[0]的代码，我没有任何想法，这是什么意思。我尝试在w3schools寻找它，并发现它们使用它，但没有解释为什么。

I see some code which makes use of a [0] at the end of document.getElementsByTagName(input)[0] and I have no ideas what that does or what it means. I tried looking for it on w3schools and found them using it , but no explanations as to why.

请帮助我了解这个后缀意味着什么。这两个命令如何不同...

Would some kind soul please help me understand what this suffix implies. How do these two commands differ...

var y = document.getElementsByTagName("input")[0]
var x = document.getElementsByTagName("input")

推荐答案

嗯， getElementsByTagName 返回一个列表的元素，所以使用 [0] 访问该列表的第一个元素。

Well, getElementsByTagName returns a list of elements, so with [0] you are accessing the first element of that list.

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