Javascript SyntaxError: 预期的表达式，得到 '<'，这是什么意思？
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SyntaxError: expected expression, got '<', what does that mean?
提问by nikel
I know this is asked a few times on S.O.
我知道这在 SO 上被问过几次
but none of the answers seem to match my situation . So, I have a a basic Html page which tries to use an external JS. The JS file tries to change the content of a paragraph defined in the HTML on a button click, but does not seem to work.
但似乎没有一个答案符合我的情况。所以，我有一个基本的 Html 页面，它尝试使用外部 JS。JS 文件试图在单击按钮时更改 HTML 中定义的段落的内容，但似乎不起作用。
I see the following errors in console :
我在控制台中看到以下错误：
1)SyntaxError: expected expression, got '<'
1）语法错误：预期的表达，得到'<'
2)ReferenceError: change is not defined
2）ReferenceError：未定义更改
JSFiddle showing exact source?(except that & tags are removed as jsfiddle - http://jsfiddle.net/p9ko4yde/
JSFiddle 显示确切来源？（除了 & 标签被删除为 jsfiddle - http://jsfiddle.net/p9ko4yde/
HTML Code :
HTML代码：
<h1> Numbers with external script:) </h1>
<p id="number">1</p>
<button type="button" onclick="change()">Toggle between 1 and 2</button>
<script src="myScript.js"></script>
</body>
</html>
JS Code :
JS代码：
<script type="text/javascript">
function change(){
var number = document.getElementById('number').innerHTML;
if(number == '1'){
document.getElementById('number').innerHTML='2';
}
else{
document.getElementById('number').innerHTML='1';
}
}
</script>
File Structure is as below:
文件结构如下：
回答by Simon Robb
You don't need the <script>tags when in an external .js file. Use these tags to embed a script inside HTML only.
<script>在外部 .js 文件中时不需要标签。使用这些标签仅在 HTML 中嵌入脚本。
回答by Hayden Schiff
The syntax error is because you have <script>tags in your JS file. When you put JavaScript in its own file like that, you don't need to surround it with script tags; that's HTML, and this is a JavaScript file.
语法错误是因为您<script>的 JS 文件中有标签。当你像这样将 JavaScript 放在它自己的文件中时，你不需要用 script 标签包围它；那是 HTML，这是一个 JavaScript 文件。
The reference error is happening because, due to the syntax error, the JS file isn't executing correctly and so the change function never got created -- fixing the syntax error should also resolve this.
引用错误的发生是因为，由于语法错误，JS 文件没有正确执行，因此从未创建更改函数——修复语法错误也应该解决这个问题。
回答by trex005
In a js file, you do not use the HTML to declare that it is a js file. So, you can drop the script tag in myScript and change it to this :
在 js 文件中，您不使用 HTML 来声明它是一个 js 文件。因此，您可以在 myScript 中删除 script 标签并将其更改为：
function change(){
var number = document.getElementById('number').innerHTML;
if(number == '1'){
document.getElementById('number').innerHTML='2';
}
else{
document.getElementById('number').innerHTML='1';
}
}
回答by Aproram
Sometimes this error happens when the Javascript referenced file doesn't exist. Make sure that the file name is correct and you have the file in place. I know your problem is solved but maybe this answer solves someone else's :)
有时当 Javascript 引用的文件不存在时会发生此错误。确保文件名正确并且文件就位。我知道您的问题已解决，但也许这个答案解决了其他人的问题:)
