1 <!DOCTYPE html>
2 <html>
3 <head>
4 <meta charset="UTF-8">
5 <title></title>
6 </head>
7 <body>
8 </body>
9 <script type="text/javascript">
10
11 var number1 = 1, number2 = 2;
12 //数据类型，js 里面是弱类型 可以进行类型自动推断
13 数字类型1 Number
14 var value1 = 5;
15 console.log(typeof 5);
16 var value2 = 5.1;
17 console.log(typeof value2);
18 类型二：undefined
19 var value3;
20 console.log(typeof value3);
21 类型三:null
22 var value4 = null;
23 console.log(typeof value4);
24 类型四 string
25 var value5 = "我很好";
26 console.log(typeof value5);
27 类型五 bool 类型
28 console.log(typeof true);
29
30 //对于 number 类型的补充
31 var value1 = 0xFF;
32 console.log(value1);
33 var value2 = 012;
34 console.log(value2);
35 </script>
36
37 </html>
原文：http://www.cnblogs.com/PowellZhao/p/5542132.html