正则表达式最详细总结（精华）

创建方式

字面量创建

let str = "abc1231dfaf123123fda";
let reg = /\d+/g;
let res = str.match(reg);
console.log(res);
VM262:4 (2) ["1231", "123123"]

划重点： / /内的内容，g为修饰符，表示全局，否则匹配一个后就停止，\d表示为数字，+表示为一个 或多个

构造函数创建

let str = "abc1231dfa123adf";
let reg = new RegExp("\\d+","g");
let res = str.match(reg);
console.log(res)
VM567:1 (2) ["1231", "123"]

划重点：如果有\d之类的需要转义

正则表达式下的方法

test

let str = "abc2323fds123";
let reg = /\d+/g;
console.log(reg.test(str));
VM795:1 true

划重点：匹配到就返回true,不到返回false

exec

let str = "abc2323fds123";
let reg = /\d+/g;
console.log(reg.test(str));
VM795:1 true
console.log(reg.exec(str))
VM885:1 ["123", index: 10, input: "abc2323fds123", groups: undefined]

划重点：exec类似match，但是是基于上次的结束去匹配

split

let  str = "abc323adf234";
undefined
let arr = str.split(3);
undefined
console.log(arr);
VM1175:1 (4) ["abc", "2", "adf2", "4"]
undefined
let arr1 = str.split(/\d+/);
undefined
console.log(arr1)
VM1298:1 (3) ["abc", "adf", ""]

search

let str = "abcdeabcde";
undefined
let reg = /e/g;
undefined
console.log(str.search(reg))
VM1516:1 4

划重点：search会忽略全局匹配，永远返回第一个匹配的下标，否则返回-1，类似IndexOf

match

let str = "abc11221defagbdc232322k"
undefined
let reg = /\d+/;
undefined
let reg1 = /\d+/g;
undefined
console.log(str.match(reg))
VM1781:1 ["11221", index: 3, input: "abc11221defagbdc232322k", groups: undefined]
undefined
console.log(str.match(reg1))
VM1871:1 (2) ["11221", "232322"]

划重点：match() 全局，非全局有区别

replace

let str = "adbad2323abcda"
let reg = /\d/g;
str.replace(reg,"*");
"adbad****abcda"

元字符

字符相关

\w：数字，字母，下划线

\W：非数字，字母，下划线

s：匹配空格

S：非空格

.：非\n,\r,\u2028,\u2029

let str = "@#223asdf";
undefined
let reg = /\w+/g;
undefined
console.log(reg.test(str));
VM2301:1 true

let str = "afb"
undefined
let reg = /a.b/;
undefined
console.log(reg.test(str));
VM2480:1 true

数量相关

{} ? + *

let reg = /ce{3}f/g    //等于  let reg = /ceeef/g
let reg = /ce{3,4}f/g    //可能出现3次到4次
let reg = /ce{1，}f/g    // 可能出现1到无穷多

划重点：？–{0，1}次
+ --{1，}
* – {0，}

？：让贪婪模式变成惰性模式

let str = "123456789";
undefined
let reg = /\d{2,4}/g; //贪婪模式
undefined
let reg1 = /\d{2,4}?/g //惰性模式
undefined
let res = str.match(reg);
undefined
console.log(res);
VM2948:1 (2) ["1234", "5678"]
undefined
let res1 = str.match(reg1)
undefined
console.log(res1)
VM3158:1 (4) ["12", "34", "56", "78"]

位置相关

^表示开始，$表示结尾 \b:边界符 \B非边界符

let str = "abcdef"
let reg = /^/g      *abcdef
let reg = /^\w/g      *bcdef
let reg = /\w\$/g     abcde*
let reg = /\$/g      abcdef*

划重点：空格是边界的一种，非\w（数字，字母，下划线）都是边界

let str = "this is a apple"; //只打印单独is
undefined
let reg = /\bis\b/g;
undefined
let res = str.match(reg);
undefined
console.log(res);
VM3399:1 ["is"]

括号相关

() 分组，提取值

let str = "abababfdfs";
undefined
let reg =/(ab){3}/g;
undefined
console.log(reg.test(str));
VM3670:1 true

let re = /(\w+)\s(\w+)/;
let str = "John Smith";
let newstr = str.replace(re, "$2, $1");
console.log(newstr);
VM4257:4 Smith, John

[]:字符集合

let str = "my name is LiLei";
undefined
let reg = /Li(L|l)ei/g;
undefined
console.log(reg.test(str));
VM4482:1 true
undefined
let reg1 = /Li[L|l]ei/g;
undefined
console.log(reg1.test(str));
VM4525:1 true

划重点：let reg = /Li(L|l) ei /g == let reg = /Li [Ll]ei/g
let reg = /[0-9]/g
let reg = /[^0-9]/ []内的^表示取反 = 为非数字 ，普通表示为开始
\d =[0-9]; \w = [a-zA-Z0-9_]

匹配模式

g:全局匹配

i：忽略大小写

m: 多行模式

s:让“.”匹配换行

u：匹配unicode编码

y:粘性模式，不可中断

零宽断言

正向零宽断言：将后面是数字的替换掉

let str = "iphone4iphone5iphone6number";
let reg = /iphone(?=\d)/g; // 肯定
let res = str.replace(reg,"苹果");
console.log(res);
苹果4苹果5苹果6number
let reg = /iphone(?!\d)/g; // 否定
iphone4iphone5iphone6number

负向零宽断言

let str = "10px20px30px";
undefined
let reg1 = /(?<=\d+)px/g; // 肯定
undefined
let reg2 = /(?<!\d+)px/g; // 否定
undefined
let res1 = str.replace(reg1,"像素");
undefined
let res2 = str.replace(reg2,"像素");
undefined
console.log(res1)
VM5370:1 10像素20像素30像素
undefined
console.log(res2)
VM5464:1 10px20px30px