javascript 字符串的连接和截取 

 1 <!DOCTYPE html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>Document</title>
 6 </head>
 7 <body>
 8     <script>
 9         //concat()：连接两个字符串返回一个新字符串，并且不会被修改
10         var str1 = "hello";
11         var str2 = "123";
12         var str3 = str1.concat(str2);
13         console.log(str1);
14         console.log(str2);
15         console.log(str3);
16 
17         var str = "I love my family!";
18         console.log(str);
19         //slice()：根据索引值和索引值截取字符串
20         console.log(str.slice(2));  //从索引截取到最后
21         console.log(str.slice(2,5));  //从索引截取，包左不包右
22         console.log(str.slice(-3));  //倒数几个
23         console.log(str.slice(5,3));  //空字符串
24 
25         //substr()：根据索引值和长度截取字符串
26         console.log(str.substr(2));  //从索引截取到最后
27         console.log(str.substr(2,6));  //从索引截~长度个字符串
28         console.log(str.substr(-3));  //倒数几个
29 
30         //substring()：根据索引和索引值截取字符串
31         console.log(str.substring(2));  //从索引截取到最后
32         console.log(str.substring(2,5));  //从索引截取~长度个字符串
33         console.log(str.substring(-1));  //全部截取
34         console.log(str.substring(5,2));  //只能调换
35     </script>
36 </body>
37 </html>

 

posted @ 2018-04-15 00:16  叶子玉  阅读(1703)  评论(0)  编辑  收藏  举报