There are three ways to introduce JavaScript: 1. Use the "
" statement to introduce; 2. Write js in the script tag Code; 3. Write the js code in an external js file, and then introduce it using the src attribute of the script tag.
The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.
There are three ways to introduce JavaScript:
1. Inline introduction:
<开始标签 on+事件类型=“js代码”></结束标签>
Inline introduction methods must be combined Events are used, but internal js and external js can not be combined with events
<body> <input type="button" onclick="alert('行内引入')" value="button" name="button"> <button 0nclick="alert(123)">点击我</button> </body>
2. Internal introduction:
In the head or body, define the script tag, and then in Write js code in the script tag
<script>
alert("这是js的内部引入");
</script>3. External introduction:
Define external js file (file ending in .js)
<script type=“text/javascript” src=“demo.js”>
Note:
script tags are generally defined in the head or body
Script tags should be used alone, either by introducing external js or by defining internal js. Do not Mix and match
external JS files, which have the characteristics of high maintainability, cacheability (load once, no need to load), convenient future expansion, and high reusability
Create a new external js file demo.js file
In the head or body, add the following code
<script type="text/javascript" src="js/demo.js"></script>
The priority order of js execution is based on the order in the code.
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