JavaScript
JS composition
ECMAScript (Basic Syntax)
describes the grammar and basic objects of the language
DOM (Document Object Model)
Describes the methods and interfaces for processing web content,
BOM (Browser Object Model)
Describes the methods and interfaces for interacting with the browser
Basic usage
Inline JS: write in element tag
Internal JS:<script>***</script>
External JS file: hello.js file is imported with script tag
<body>
<!--
JS的三种使用方式
1. 行内JS 在html标签上直接写JS代码
2. 内部JS 在<script></script>写JS代码 ，可放置在页面任意位置
3. 外部JS 定义JS文件，通过<script></script>的src属性引入JS文件
注意:如果script标签设置了scr属性,则script标签内容不再生效
-->
<!--行内JS-->
<button onclick="alert('hello World');" type="submit">提交</button>
<!--内部JS-->
<script type="text/javascript">
alert("这是一个按钮");
</script>
<!--引入外部JS文件-->
<script src="js/test.js" type="text/javascript" charset="utf-8"></script>
</body>