2020.1.31字符串_查找方法

1    var str="abcabcabc";
2    
3    alert(str.indexOf("abc"));
4    //0
5    alert(str.indexOf("abcd"));
6    //-1
7    alert(str.indexOf("abc",1));
8    //3

 1             var str="hello world! i love you!";
 2             alert(str.replace("love","like"));
 3             
 4             var str2="hello  hi hi hi world!";
 5             alert(str2.replace("hi","hello"));
 6             //只能将第一次出现了 "hi"给replace为"hello"
 7             
 8             alert(str2.replace(/hi/g,"hello"));
 9             //g:所有. 要想替换所有,必须使用正则表达式
10             
11             var str3="hello Hi hi Hi";
12             alert(str3.replace(/hi/ig,"hello"));
13             //i:忽略大小写