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							- <!DOCTYPE html>
 
- <html lang="en">
 
- <head>
 
-     <meta charset="UTF-8">
 
-     <meta name="viewport" content="width=device-width, initial-scale=1.0">
 
-     <title>Document</title>
 
- </head>
 
- <body>
 
-     <!-- 
 
-     
 
-         弱语言类型
 
-             数据 决定 类型
 
-         检验类型的方法:
 
-         typeof xxx   
 
-           null类型通过typeof会判断成object 
 
-         js数据类型:
 
-             基本数据类型:
 
-                 number 数字
 
-                 string 字符串
 
-                 null 空
 
-                 undefined 未定义的
 
-                 boolean 布尔值(true/false)
 
-             引用数据类型 
 
-                 Object(数组[]/对象{}/函数)
 
-     -->
 
-     <script>
 
-         var a = 10;
 
-         console.log(typeof a);//number
 
-         var b = '10';
 
-         console.log(typeof b);//string 
 
-         var c =  true;
 
-         console.log(typeof c);//boolean 
 
-         var d =  false;
 
-         console.log(typeof d);//boolean 
 
-         var e;
 
-         console.log(typeof e);//undefined 
 
-         var f = null; // null
 
-         console.log(typeof f);//null类型通过typeof会判断成object 
 
-         var g = [1,2,3];
 
-         console.log(typeof g);
 
-         var h = {
 
-             name:'小明'
 
-         }
 
-         console.log(typeof h)
 
-     </script>
 
- </body>
 
- </html>
 
 
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