字符串与正则的扩展

时间 2019-11-26

原文原文链接

一、字符串的扩展

Unicode - \u0000 ~ \uFFFF正则表达式

'\{u0061}'
   // a 

   '\uD842\uDfB7'
   "\u{20BB7}"
   // "𠮷"

字符串遍历器 - 识别大于0xFFFFspa

let text2 = String.fromCodePoint(0x20BB7);

    for(let i = 0;i < text2.length;i++){
        console.log(text2[i]);
    }
    // �
    // � 

    for (let i of text){
        console.log(i);
    }
    // "𠮷"

模板字符串 - 保留全部空格与换行prototype

const getName = () => 'Iven';
   const myName = 'Eric';
   `\`Hello\` ${getName()},I am ${myName}`

   //"`Hello` Iven,I am Eric"

标签模板code

alert`111`;
   // alert(111);

   func`This ${ a + b} is ${ a * b}`;
   // func(['This', 'is', ''],a + b, a * b);

   <div>
   	<span>1111</span>
   </div>

新增方法字符串

fromCodePoint - 从Unicode码点返回对应字符

String.fromCodePoint(0x78, 0x1f680, 0x79);
   // x🚀y

String.raw - 返回一个包括\在内的字符串

String.raw`\`Hello\` I am`;
   // \`Hello\` I am

   `\`Hello\` I am`
   // `Hello` I am

   String.raw({ raw: 'test'}, 1,2,3,4);
   String.raw({ raw: ['t','e','s','t']}, 1,2,3,4);
   // t1e2s3t

codePointAt - 返回一个字符的码点（10进制）

let s = '𠮷a';
   s.codePointAt(0).toString(16);
   s.codePointAt(2).toString(16);
   // 61

includes - 是否包含参数字符串

const string = 'Hello world!';
   string.includes('wo');
   // true

startsWith - 是否以某一个字符串开头

const string = 'Hello world';
   string.includes('He');
   // true

endsWith - 是否以某一个字符串结尾

const string = 'Hello world';
   string.includes('world');
   // true

repeat - 将原字符串重复n次

`Hello`.repeat(2.9);
   // HelloHello

   `Hello`.repeat(-0.9);
   // ""

padStart - 字符串补全长度

`hello`.padStart(10,'0123456789');
   // 01234hello

padEnd

`hello`.padEnd(10,'0123456789');
   // hello01234

trimStart、trimEnd - 去除空格，换行，tab
```
'  abc  '.trimStart();
   // abc
```

matchAll - 返回正则表达式全部匹配

for(s of 'abcabcabc'.matchAll('ab')) {
       console.log(s)
   }

二、正则的扩展

RegExp - 指定修饰符
```
new RegExp(/abc/ig,'i');
    // /abc/i
```

字符串正则 - 内部改成调用RegExp方法

RegExp.prototype[Symbol.match];
   RegExp.prototype[Symbol.replace];
   RegExp.prototype[Symbol.search];
   RegExp.prototype[Symbol.split];

y修饰符 - 全局粘连匹配

const s = 'abcdabcdabc';
   const reg1 = new RegExp('abc', 'g');
   const reg2 = new RegExp('abc', 'y');

   reg1.exec(s);
   reg2.exec(s);

sticky - 是否使用了y修饰符

const reg = /hello\d/y;
   reg.sticky;
   // true

flags - 返回正则表达式的修饰符
```
/abc/ig.flags
   // gi
```
s - 匹配一切字符(.不能匹配回车、换行等行终止符)
```
/week.month/s.test('week\nbar');
   // false
```

组别名(当咱们使用正则匹配时，能够把它赋给一个变量)

// 共同定义
   const RE_DATE = /(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/;
   const matchObj = RE_DATE.exec('1999-12-31');

   const year = matchObj.groups.year;
   matchObj[1];
   // 1999 

   const month = matchObj.groups.month;
   matchObj[2];
   // 12 

   const day = matchObj.groups.day;
   matchObj[3];
   // 31 

   let { groups: { one, two } } = /^(?<one>.*):(?<two>.*)$/u.exec('week:month');

matchAll - 返回正则表达式全部匹配 - 迭代器

for(s of 'abcabcabc'.matchAll('ab')) {
       console.log(s)
   }