Javascrip 正则表达式速查表

const regex = /yes|no|maybe/;Copy

const caseInsensitiveRegex = /ignore case/i; //注意最后的 i
const testString = 'We use the i flag to iGnOrE CasE';
caseInsensitiveRegex.test(testString); // 由于字符串中的 "iGnOrE CasE" 在忽略大小写的情况下与 “ignore case” 相同，故命中返回 true
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const match = "Hello World!".match(/hello/i); // 常量 match = "Hello"Copy

const testString = "Repeat repeat rePeAT";
const regexWithAllMatches = /Repeat/gi; //最后的 g 表示全部。
testString.match(regexWithAllMatches); // 返回 ["Repeat", "repeat", "rePeAT"]
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// 匹配 "cat", "BAT", "fAT", "mat" -所有都是一个字符后跟 "at"
const regexWithWildcard = /.at/gi; //全部，忽略大小写
const testString = "cat BAT cupcake fAT mat dog";
const allMatchingWords = testString.match(regexWithWildcard); // ["cat", "BAT", "fAT", "mat"]
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const regexWithCharRange = /[a-e]at/;
const catString = "cat";
const batString = "bat";
const fatString = "fat";

regexWithCharRange.test(catString); // true
regexWithCharRange.test(batString); // true
regexWithCharRange.test(fatString); // false
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const regexWithLetterAndNumberRange = /[a-z0-9]/ig;
const testString = "Emma19382";
testString.match(regexWithLetterAndNumberRange) // 全匹配，返回原始串 "Emma19382"
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const allCharsNotVowels = /[^aeiou]/gi;
const allCharsNotVowelsOrNumbers = /[^aeiou0-9]/gi;Copy

const oneOrMoreAsRegex = /a+/gi;
const oneOrMoreSsRegex = /s+/gi;
const cityInFlorida = "Tallahassee";

cityInFlorida.match(oneOrMoreAsRegex); // ['a', 'a', 'a'];
cityInFlorida.match(oneOrMoreSsRegex); // ['ss'];
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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
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const testString = "catastrophe";
const greedyRexex = /c[a-z]*t/gi;
const lazyRegex = /c[a-z]*?t/gi;

testString.match(greedyRexex); // ["catast"]，其中 [a-z]* 匹配了 "atas"
testString.match(lazyRegex); // ["cat"]，其中 [a-z]*? 仅匹配了 "a"
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const emmaAtFrontOfString = "Emma likes cats a lot.";
const emmaNotAtFrontOfString = "The cats Emma likes are fluffy.";
const startingStringRegex = /^Emma/; //匹配行首是 "Emma"

startingStringRegex.test(emmaAtFrontOfString); // true
startingStringRegex.test(emmaNotAtFrontOfString); // false
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const emmaAtBackOfString = "The cats do not like Emma";
const emmaNotAtBackOfString = "Emma loves the cats";
const startingStringRegex = /Emma$/; //匹配以 "Emma" 结尾的字符串

startingStringRegex.test(emmaAtBackOfString); // true
startingStringRegex.test(emmaNotAtBackOfString); // false
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const longHand = /[A-Za-z0-9_]+/; //代表所有字母和数字的正则的长写法
const shortHand = /\w+/; //代表所有字母和数字的正则的短写法
const numbers = "42";
const myFavoriteColor = "magenta";

longHand.test(numbers); // true
shortHand.test(numbers); // true
longHand.test(myFavoriteColor); // true
shortHand.test(myFavoriteColor); // true
//字母和数字都匹配Copy

const noAlphaNumericCharRegex = /\W/gi;
const weirdCharacters = "!_$!!";
const alphaNumericCharacters = "ab283AD";

noAlphaNumericCharRegex.test(weirdCharacters); // true
noAlphaNumericCharRegex.test(alphaNumericCharacters); // falseCopy

const digitsRegex = /\d/g;
const stringWithDigits = "My cat eats $20.00 worth of food a week.";

stringWithDigits.match(digitsRegex); // ["2", "0", "0", "0"]
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const nonDigitsRegex = /\D/g;
const stringWithLetters = "101 degrees";

stringWithLetters.match(nonDigitsRegex); // [" ", "d", "e", "g", "r", "e", "e", "s"]
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const sentenceWithWhitespace = "I like cats!"
var spaceRegex = /\s/g;
whiteSpace.match(sentenceWithWhitespace); // [" ", " "]
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const sentenceWithWhitespace = "C a t"
const nonWhiteSpaceRegex = /\D/g;
sentenceWithWhitespace.match(nonWhiteSpaceRegex); // ["C", "a", "t"]
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const regularHi = "hi";
const mediocreHi = "hiii";
const superExcitedHey = "heeeeyyyyy!!!";
const excitedRegex = /hi{1,4}/; // i 紧接在 h 后出现1到4次都匹配

excitedRegex.test(regularHi); // true
excitedRegex.test(mediocreHi); // true
excitedRegex.test(superExcitedHey); //false
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const regularHi = "hi";
const mediocreHi = "hiii";
const superExcitedHey = "heeeeyyyyy!!!";
const excitedRegex = /hi{2,}/; // i 紧接在 h 后2次即匹配（可多不能少）

excitedRegex.test(regularHi); // false
excitedRegex.test(mediocreHi); // true
excitedRegex.test(superExcitedHey); //false
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const regularHi = "hi";
const bestHi = "hii";
const mediocreHi = "hiii";
const excitedRegex = /hi{2}/; // 表示仅 i 在 h 后出现2次匹配

excitedRegex.test(regularHi); // false
excitedRegex.test(bestHi); // true
excitedRegex.test(mediocreHi); //false
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const britishSpelling = "colour";
const americanSpelling = "Color";
const languageRegex = /colou?r/i;

languageRegex.test(britishSpelling); // true
languageRegex.test(americanSpelling); // trueCopy