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Does javascript code have to be written in html?

青灯夜游

Feb 16, 2022 pm 03:20 PM

htmljavascript

Javascript code does not have to be written in html, it can also be written in a script file with the extension ".js", and then referenced using the script tag in html, the syntax "".

Does javascript code have to be written in html?

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

JavaScript programs cannot run independently and can only be executed in the host environment. Under normal circumstances, JavaScript code can be placed in the web page and run with the help of the browser environment.

In html, there are three ways to use javascript code:

Embedding JavaScript code in HTML documents
In Write JavaScript code in the script file, use script tag reference

#Embed JavaScript code in HTML document

Embed JavaScript script in HTML page required Using the <script> tag, users can write JavaScript code directly in the <script> tag</script>

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>第一个JavaScript程序</title>
    <script type="text/javascript">
        document.write("<h1 id="php中文网-php-cn">php中文网：php.cn</h1>");
    </script>
</head>
<body></body>
</html>

Write JavaScript code in a script file

JavaScript programs can not only Place it directly in the HTML document or in a JavaScript script file. JavaScript script files are text files with a .js extension that can be edited using any text editor.

Just create a .js file and write js code in the file, for example:

alert("php中文网：php.cn");

Then in HTML, insert a <script> tag. Define the src attribute and set the attribute value to a URL string pointing to an external JavaScript file. The code is as follows: <br/></script>

<script type="text/javascript" src="test.js"></script>

Note:

When using the <script> tag to include external JavaScript files, the default file type is Javascript. Therefore, regardless of whether the loaded file has a .js extension or not, the browser will parse it as a JavaScript script. </script>
The <script> tag that defines the src attribute should no longer contain JavaScript code. If the code is embedded, only the external JavaScript file will be downloaded and executed, and the embedded code will be ignored. </script>

[Related recommendations: javascript learning tutorial]

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