getElementsByTagName似乎不起作用 [英] getElementsByTagName does not seem to work
问题描述
当我通过Id获取元素时,它工作得很好。但是与getElementsByTagName()相同的方法不会。
另外如果我使用querySelector(),它可以工作。但是如果我使用querySelectorAll(),则返回相同的错误。
test.html:15未捕获TypeError:无法设置未定义的属性color
这是我的代码:
< DOCTYPE! HTML>
< html>
< head>
< / head>
< body>
< h1> Hello World< / h1>
< p id =par> Hello World< / p>
< script>
var par = document.getElementById('par');
par.style.color =red
var heading = document.getElementsByTagName(h1);
heading.style.color =red
< / script>
< / body>
< / html>
您可以清楚地看到文档,getElementsByTagName
返回一个元素数组,而不是单个元素。 p>
所以你必须遵循正确的索引,否则会抛出一个例外,就像你的情况一样。
Can someone please explain why my code is not working !!
When I get the element By Id it works perfectly fine. But the same method with getElementsByTagName() does not.
Also if I use querySelector(), it works. However if I use querySelectorAll() the same error returns.
test.html:15 Uncaught TypeError: Cannot set property 'color' of undefined
here is my code:
<DOCTYPE! html>
<html>
<head>
</head>
<body>
<h1>Hello World</h1>
<p id="par">Hello World</p>
<script>
var par = document.getElementById('par');
par.style.color = "red"
var heading = document.getElementsByTagName("h1");
heading.style.color = "red"
</script>
</body>
</html>
As you can clearly see document,getElementsByTagName
returns an array of elements, not a single element.
So you have to follow proper indexing otherwise it will throw an exception as in your case.
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