Javascript 更改 textarea 的值
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Changing value of textarea
提问by benone
I write this script to change the value of a textarea but I fail to do so. What's wrong with my code?
我编写此脚本来更改 textarea 的值，但我没有这样做。我的代码有什么问题？
<html>
<head>
<script type="text/javascript">
document.getElementsByName("status").innerHTML = "hi";
document.getElementsByName("status").title= "hi";
document.getElementsByName("status").placeholder= "hi";
</script>
</head>
<body>
<textarea placeholder="What's on your mind?" onfocus="window.UIComposer && UIComposer.focusInstance("c4d981e9a2c98b0483252333");" name="status" id="c4d981e9a2c98b0483252333_input" title="What's on your mind?" class="DOMControl_placeholder UIComposer_TextArea">What's on your mind?</textarea>
</body>
</html>
回答by David says reinstate Monica
Iif you try using:
如果您尝试使用：
var textarea = document.getElementById('c4d981e9a2c98b0483252333_input');
textarea.value = 'hi';
It should work.
它应该工作。
Otherwise, because of the way getElementsByNameworks, you'd need to provide an index (zero-based) to the call to identify which of the textareas you want to work with:
否则，由于工作方式getElementsByName，您需要为调用提供一个索引（从零开始）以标识您要使用的文本区域：
var textarea = document.getElementByName('status')[0]; // selects the first element of name 'status'
textarea.value = 'hi';
回答by Quentin
Two problems
两个问题
First, document.getElementsByNamereturns a NodeList (which is like an array), not a single element.
首先，document.getElementsByName返回一个 NodeList（就像一个数组），而不是单个元素。
Second, you do nothing to delay the execution of the JS until the element actually exists. So it won't find it anyway.
其次，您不会延迟 JS 的执行，直到元素实际存在。所以无论如何也找不到。
- Change to
document.getElementsByName("status")[0] - Move the
<script>element so it appears afterthe textarea.
- 改成
document.getElementsByName("status")[0] - 移动
<script>元素，使其出现在textarea 之后。
I wouldn't be comfortable with using innerHTMLto modify a form control either. I'd switch to valueinstead.
我也不喜欢innerHTML用来修改表单控件。我会改用value。
回答by Quentin
<script type="text/javascript">
document.getElementsByName("status")[0].value = "hi";
</script>
回答by MuniR
put this script in the body
把这个脚本放在正文中
<script type="text/javascript">
document.getElementById("status").value= "hi";
</script>
change getElementsByName to getElementById
将 getElementsByName 更改为 getElementById
getElementsByName -> returns array of elements getElementById -> returns single control..
getElementsByName -> 返回元素数组 getElementById -> 返回单个控件..
then put the script in between body tags not in header.....
然后将脚本放在正文标记之间而不是标题中.....
回答by Farzin Zaker
<html>
<head>
</head>
<body>
<textarea placeholder="What's on your mind?" onfocus="window.UIComposer && UIComposer.focusInstance("c4d981e9a2c98b0483252333");" name="status" id="c4d981e9a2c98b0483252333_input" title="What's on your mind?" class="DOMControl_placeholder UIComposer_TextArea">What's on your mind?</textarea>
<script type="text/javascript">
document.getElementById("c4d981e9a2c98b0483252333_input").value = "hi";
document.getElementsByName("status")[0].value = "hi";
</script>
</body>
</html>
