JS基础_自增自减练习

 1 <!DOCTYPE html>
 2 <html>
 3     <head>
 4         <meta charset="UTF-8">
 5         <title></title>
 6         <script type="text/javascript">
 7         
 8             var n1=10;
 9             var n2=20;
10             
11             var n = n1++;     //后置，先赋值，即n=10，再n1自增1为11
12             
13             console.log(n);   //10
14             console.log(n1);  //11
15             
16             n = ++n1          //前置，n1先自增1为12，再赋值给n，即n为12
17             console.log(n);   //12
18             console.log(n1);  //12
19             
20             n = n2--;         //后置，先把n2赋值给n，即n为20，再自减1，则n2为19
21             console.log(n);   //20
22             console.log(n2);  //19
23             
24             n = --n2;         //前置，n2先自减1，即n2为18，再赋值给n，即n为18
25             console.log(n);   //18
26             console.log(n2);  //18
27             
28             
29             
30         </script>
31     </head>
32     <body>
33     </body>
34 </html>