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正则表达式或“regex”用于婚配字符串的各个部份 下面是我建立正则表达式的备忘单。
婚配正则
运用 .test()
要领
let testString = "My test string";
let testRegex = /string/;
testRegex.test(testString);
婚配多个形式
运用操纵标记 |
const regex = /yes|no|maybe/;
疏忽大小写
运用i
标志示意疏忽大小写
const caseInsensitiveRegex = /ignore case/i;
const testString = 'We use the i flag to iGnOrE CasE';
caseInsensitiveRegex.test(testString); // true
提取变量的第一个婚配项
运用 .match()
要领
const match = "Hello World!".match(/hello/i); // "Hello"
提取数组中的一切婚配项
运用 g
标志
const testString = "Repeat repeat rePeAT";
const regexWithAllMatches = /Repeat/gi;
testString.match(regexWithAllMatches); // ["Repeat", "repeat", "rePeAT"]
婚配恣意字符
运用通配符.
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"]
用多种能够性婚配单个字符
- 运用字符类,你能够运用它来定义要婚配的一组字符
- 把它们放在方括号里
[]
//婚配 "cat" "fat" and "mat" 但不婚配 "bat"
const regexWithCharClass = /[cfm]at/g;
const testString = "cat fat bat mat";
const allMatchingWords = testString.match(regexWithCharClass); // ["cat", "fat", "mat"]
婚配字母表中的字母
运用字符集内的局限 [a-z]
const regexWidthCharRange = /[a-e]at/;
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
婚配特定的数字和字母
你还能够运用连字符来婚配数字
const regexWithLetterAndNumberRange = /[a-z0-9]/ig;
const testString = "Emma19382";
testString.match(regexWithLetterAndNumberRange) // true
婚配单个未知字符
要婚配您不想具有的一组字符,运用否认字符集 ^
const allCharsNotVowels = /[^aeiou]/gi;
const allCharsNotVowelsOrNumbers = /[^aeiou0-9]/gi;
婚配一行中涌现一次或屡次的字符
运用 +
标志
const oneOrMoreAsRegex = /a+/gi;
const oneOrMoreSsRegex = /s+/gi;
const cityInFlorida = "Tallahassee";
cityInFlorida.match(oneOrMoreAsRegex); // ['a', 'a', 'a'];
cityInFlorida.match(oneOrMoreSsRegex); // ['ss'];
婚配一连涌现零次或屡次的字符
运用星号 *
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
惰性婚配
- 字符串中与给定请求婚配的最小部份
- 默许情况下,正则表达式是贪欲的(婚配满足给定请求的字符串的最长部份)
运用
?
阻挠贪欲形式(惰性婚配 )
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"]
婚配肇端字符串形式
要测试字符串开首的字符婚配,请运用插进去标记^
,但要放大开首,不要放到字符集合
const emmaAtFrontOfString = "Emma likes cats a lot.";
const emmaNotAtFrontOfString = "The cats Emma likes are fluffy.";
const startingStringRegex = /^Emma/;
startingStringRegex.test(emmaAtFrontOfString); // true
startingStringRegex.test(emmaNotAtFrontOfString); // false
婚配完毕字符串形式
运用 $
来推断字符串是不是是以划定的字符末端
const emmaAtBackOfString = "The cats do not like Emma";
const emmaNotAtBackOfString = "Emma loves the cats";
const startingStringRegex = /Emma$/;
startingStringRegex.test(emmaAtBackOfString); // true
startingStringRegex.test(emmaNotAtBackOfString); // false
婚配一切字母和数字
运用\word
简写
const longHand = /[A-Za-z0-9_]+/;
const shortHand = /\w+/;
const numbers = "42";
const myFavoriteColor = "magenta";
longHand.test(numbers); // true
shortHand.test(numbers); // true
longHand.test(myFavoriteColor); // true
shortHand.test(myFavoriteColor); // true
除了字母和数字,其他的都要婚配
用\W
示意 \w
的反义
const noAlphaNumericCharRegex = /\W/gi;
const weirdCharacters = "!_$!!";
const alphaNumericCharacters = "ab283AD";
noAlphaNumericCharRegex.test(weirdCharacters); // true
noAlphaNumericCharRegex.test(alphaNumericCharacters); // false
婚配一切数字
你能够运用字符集[0-9]
,或许运用简写 \d
const digitsRegex = /\d/g;
const stringWithDigits = "My cat eats $20.00 worth of food a week.";
stringWithDigits.match(digitsRegex); // ["2", "0", "0", "0"]
婚配一切非数字
用\D
示意 \d
的反义
const nonDigitsRegex = /\D/g;
const stringWithLetters = "101 degrees";
stringWithLetters.match(nonDigitsRegex); // [" ", "d", "e", "g", "r", "e", "e", "s"]
婚配空格
运用 \s
来婚配空格和回车符
const sentenceWithWhitespace = "I like cats!"
var spaceRegex = /\s/g;
whiteSpace.match(sentenceWithWhitespace); // [" ", " "]
婚配非空格
用\S
示意 \s
的反义
const sentenceWithWhitespace = "C a t"
const nonWhiteSpaceRegex = /\S/g;
sentenceWithWhitespace.match(nonWhiteSpaceRegex); // ["C", "a", "t"]
婚配的字符数
你能够运用 {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); // true
excitedRegex.test(mediocreHi); // true
excitedRegex.test(superExcitedHey); //false
婚配最低个数的字符数
运用{下界, }
定义起码数目的字符请求,下面示例示意字母 i
最少要涌现2次
const regularHi = "hi";
const mediocreHi = "hiii";
const superExcitedHey = "heeeeyyyyy!!!";
const excitedRegex = /hi{2,}/;
excitedRegex.test(regularHi); // false
excitedRegex.test(mediocreHi); // true
excitedRegex.test(superExcitedHey); //false
婚配准确的字符数
运用{requiredCount}
指定字符请求的确实数目
const regularHi = "hi";
const bestHi = "hii";
const mediocreHi = "hiii";
const excitedRegex = /hi{2}/;
excitedRegex.test(regularHi); // false
excitedRegex.test(bestHi); // true
excitedRegex.test(mediocreHi); //false
婚配0次或1次
运用 ?
婚配字符 0 次或1次
const britishSpelling = "colour";
const americanSpelling = "Color";
const languageRegex = /colou?r/i;
languageRegex.test(britishSpelling); // true
languageRegex.test(americanSpelling); // true
代码布置后能够存在的BUG没法及时晓得,预先为了处理这些BUG,花了大批的时候举行log 调试,这边顺便给人人引荐一个好用的BUG监控东西 Fundebug。
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