字符串一些常用方法

字符串的常用方法

1、toLocaleLowerCase()：把字符串变为小写

let str = 'hjhjkKHhkKFFTfchhuD'
let res1 = str.toLocaleLowerCase()
console.log(res1);  //hjhjkkhhkkfftfchhud

2、toUpperCase()：把字符串变为大写

let str = 'hjhjkKHhkKFFTfchhuD'   
let res2 = str.toUpperCase()
console.log(res2); //HJHJKKHHKKFFTFCHHUD

3、indexOf() ： 搜索某一个子字符串在字符串中的位置，如果有，则返回第一个位置的索引，如果没有则返回-1

let str = 'hjhjkKHhkKFFTfchhuD'   
let res3 = str.indexOf('f')
console.log(res3); //13
let res4 = str.indexOf('a')
console.log(res4);  //-1

4、split()： 用特定的符号把字符穿分割成数组

let str1 = 'zhangsanfeng zhangsanfeng zhangsanfeng'
let str2 = 'zhangsanfeng-zhangsanfeng-zhangsanfeng'
let str3 = 'zhangsanfeng,zhangsanfeng,zhangsanfeng'
//用空格分割字符串
let arr1 = str1.split(' ')
console.log(arr1); //(3) ['zhangsanfeng', 'zhangsanfeng', 'zhangsanfeng']
// 用中横线（-）分割字符串
let arr2 = str2.split('-')
console.log(arr2); //(3) ['zhangsanfeng', 'zhangsanfeng', 'zhangsanfeng']
// 用逗号（,）分割字符串
let arr3 = str3.split(',')
console.log(arr3); //(3) ['zhangsanfeng', 'zhangsanfeng', 'zhangsanfeng']

5、 substr(开始索引,个数): 返回从指定下标开始指定长度的的子字符串

let nameAtr = 'zhangsanfenglisigouwanglaowu'
let res = nameAtr.substr(12, 7)
console.log(res); //lisigou