匹配正则使用.test方法匹配多个模式使用操作符号

  正则表达式或“regex”用于匹配字符串的各个部分，下面是作者创建正则表达式的备忘单js正则匹配多个字符串，供大家学习参考。

  匹配正则

  使用.test()方法

let testString = "My test string";`let testRegex = /string/;`testRegex.test(testString);

  匹配多个模式

  使用操作符号|

const regex = /yes|no|maybe/; 

  忽略大小写

  使用i标志表示忽略大小写

const caseInsensitiveRegex = /ignore case/i;`const testString = 'We use the i flag to iGnOrE CasE';`caseInsensitiveRegex.test(testString); // true

  提取变量的第一个匹配项

  使用.match()方法

const match = "Hello World!".match(/hello/i); // "Hello"

  提取数组中的所有匹配项

  使用g标志

const testString = "Repeat repeat rePeAT";`const regexWithAllMatches = /Repeat/gi;`testString.match(regexWithAllMatches); // ["Repeat", "repeat", "rePeAT"] 

  匹配任意字符

  使用通配符.作为任何字符的占位符

// To match "cat", "BAT", "fAT", "mat"`const regexWithWildcard = /.at/gi;const testString = "cat BAT cupcake fAT mat dog";const allMatchingWords = testString.match(regexWithWildcard); // ["cat", "BAT", "fAT", "mat"] `用多种可能性匹配单个字符

//匹配 "cat" "fat" and "mat" 但不匹配 "bat"`const regexWithCharClass = /[cfm]at/g;const testString = "cat fat bat mat";const allMatchingWords = testString.match(regexWithCharClass); // ["cat", "fat", "mat"] `

  匹配字母表中的字母

  使用字符集内的范围[a-z]

const regexWidthCharRange = /[a-e]at/;` const regexWithCharRange = /[a-e]at/;const catString = "cat";const batString = "bat";const fatString = "fat"; regexWithCharRange.test(catString); // trueregexWithCharRange.test(batString); // trueregexWithCharRange.test(fatString); // false`

  匹配特定的数字和字母

  你还可以使用连字符来匹配数字

const regexWithLetterAndNumberRange = /[a-z0-9]/ig;`const testString = "Emma19382";`testString.match(regexWithLetterAndNumberRange) // true

  匹配单个未知字符

  要匹配您不想拥有的一组字符，使用否定字符集^

const allCharsNotVowels = /[^aeiou]/gi;`const allCharsNotVowelsOrNumbers = /1/gi;`

  匹配一行中出现一次或多次的字符

  使用+标志

const oneOrMoreAsRegex = /a+/gi;`const oneOrMoreSsRegex = /s+/gi;const cityInFlorida = "Tallahassee"; cityInFlorida.match(oneOrMoreAsRegex); // ['a', 'a', 'a'];cityInFlorida.match(oneOrMoreSsRegex); // ['ss'];   `

  匹配连续出现零次或多次的字符

  使用星号*

const zeroOrMoreOsRegex = /hi*/gi;`const normalHi = "hi";const happyHi = "hiiiiii";const twoHis = "hiihii";const bye = "bye"; normalHi.match(zeroOrMoreOsRegex); // ["hi"]happyHi.match(zeroOrMoreOsRegex); // ["hiiiiii"]twoHis.match(zeroOrMoreOsRegex); // ["hii", "hii"]bye.match(zeroOrMoreOsRegex); // null` 

  惰性匹配

 const testString = "catastrophe";` const greedyRexex = /c[a-z]*t/gi; const lazyRegex = /c[a-z]*?t/gi;  testString.match(greedyRexex); // ["catast"] testString.match(lazyRegex); // ["cat"] `

  匹配起始字符串模式

  要测试字符串开头的字符匹配，请使用插入符号^，但要放大开头，不要放到字符集中

const emmaAtFrontOfString = "Emma likes cats a lot.";`const emmaNotAtFrontOfString = "The cats Emma likes are fluffy.";const startingStringRegex = /^Emma/; startingStringRegex.test(emmaAtFrontOfString); // truestartingStringRegex.test(emmaNotAtFrontOfString); // false ` 

  匹配结束字符串模式

  使用$来判断字符串是否是以规定的字符结尾

const emmaAtBackOfString = "The cats do not like Emma";`const emmaNotAtBackOfString = "Emma loves the cats";const startingStringRegex = /Emma$/; startingStringRegex.test(emmaAtBackOfString); // truestartingStringRegex.test(emmaNotAtBackOfString); // false `

  匹配所有字母和数字

  使用word简写

const longHand = /[A-Za-z0-9_]+/;`const shortHand = /w+/;const numbers = "42";const myFavoriteColor = "magenta"; longHand.test(numbers); // trueshortHand.test(numbers); // truelongHand.test(myFavoriteColor); // true`shortHand.test(myFavoriteColor); // true

  除了字母和数字，其他的都要匹配

  用W表示w的反义

const noAlphaNumericCharRegex = /\W/gi;`const weirdCharacters = "!_$!!";const alphaNumericCharacters = "ab283AD"; noAlphaNumericCharRegex.test(weirdCharacters); // truenoAlphaNumericCharRegex.test(alphaNumericCharacters); // false` 

  匹配所有数字

  你可以使用字符集[0-9]js正则匹配多个字符串，或者使用简写d

const digitsRegex = /\d/g;`const stringWithDigits = "My cat eats $20.00 worth of food a week."; stringWithDigits.match(digitsRegex); // ["2", "0", "0", "0"]` 

  匹配所有非数字

  用D表示d的反义

const nonDigitsRegex = /\D/g;`const stringWithLetters = "101 degrees"; stringWithLetters.match(nonDigitsRegex); // [" ", "d", "e", "g", "r", "e", "e", "s"]`

  匹配空格

  使用s来匹配空格和回车符

const sentenceWithWhitespace = "I like cats!"`var spaceRegex = /s/g;`whiteSpace.match(sentenceWithWhitespace); // [" ", " "]

  匹配非空格

  用S表示s的反义

const sentenceWithWhitespace = "C a t"`const nonWhiteSpaceRegex = /S/g;sentenceWithWhitespace.match(nonWhiteSpaceRegex); // ["C", "a", "t"] `

  匹配的字符数

  你可以使用{下界，上界}指定一行中的特定字符数

const regularHi = "hi";`const mediocreHi = "hiii";const superExcitedHey = "heeeeyyyyy!!!";const excitedRegex = /hi{1,4}/; excitedRegex.test(regularHi); // trueexcitedRegex.test(mediocreHi); // trueexcitedRegex.test(superExcitedHey); //false`

  匹配最低个数的字符数

  使用{下界, }定义最少数量的字符要求,下面示例表示字母i至少要出现2次

const regularHi = "hi";`const mediocreHi = "hiii";const superExcitedHey = "heeeeyyyyy!!!";const excitedRegex = /hi{2,}/; excitedRegex.test(regularHi); // falseexcitedRegex.test(mediocreHi); // trueexcitedRegex.test(superExcitedHey); //false`

  匹配精确的字符数

  使用{requiredCount}指定字符要求的确切数量

const regularHi = "hi";`const bestHi = "hii";const mediocreHi = "hiii";const excitedRegex = /hi{2}/; excitedRegex.test(regularHi); // falseexcitedRegex.test(bestHi); // trueexcitedRegex.test(mediocreHi); //false `

  匹配0次或1次

  使用?匹配字符 0 次或1次

const britishSpelling = "colour";`const americanSpelling = "Color";const languageRegex = /colou?r/i; languageRegex.test(britishSpelling); // truelanguageRegex.test(americanSpelling); // true`