JavaScript 变量
为什么 SurveyName 的值没有改变？
<script type = 'text/javascript'>
surveyName = "catNull";
function test(){
window['surveyName'] = "catTest";
}
</script>
</head>
<body>
<input onclick = 'test()' id = 'cat' class = 'test' type = 'button' value = 'category' />
<script>
document.write('<input id = "survey" class = "test" type = "button" value = "'+surveyName+'" />');
</script>
Why doesn't surveyName's value change?
<script type = 'text/javascript'>
surveyName = "catNull";
function test(){
window['surveyName'] = "catTest";
}
</script>
</head>
<body>
<input onclick = 'test()' id = 'cat' class = 'test' type = 'button' value = 'category' />
<script>
document.write('<input id = "survey" class = "test" type = "button" value = "'+surveyName+'" />');
</script>
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评论（4）
它确实改变了。
但是，您永远不会观察到变化。
It does change.
However, you never observe the change.
因为您不更改
input对象的值，仅更改变量。该元素独立于变量。
如果您想更改浏览器显示的内容，您必须执行以下操作：
Because you don't change
inputobject's value, only the variable.The element is independent of the variable.
If you want to change what the browser shows, you must do:
因为你还没有点击输入。
Because you did not click on the input yet.
确实如此。但是您已经将变量输出到页面，并且您输出的内容不会改变。
如果您想更改
input的值：这是可行的，因为您已为元素分配了
id值“survey”，因此您可以通过document.getElementById 检索元素传入该值id，并使用元素的value属性 设置值。It does. But you've already output the variable to the page, and what you've output doesn't change.
If you want to change the
input's value:That works because you've assigned the element the
idvalue"survey", so you can retrieve the element viadocument.getElementByIdpassing in thatid, and use the element'svalueproperty to set the value.