JavaScript正則表達字典

測試正則表達式

• 使用.test()方法

let testString = "My test string";
let testRegex = /string/;
testRegex.test(testString);
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• 測試多項匹配使用OR運算符(|)

let testString = "My test string";
const regex = /test|My|string/;
regex.test(testString);
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• 使用(i)忽略大小寫

let testString = "My test string";
const ignoreReg = /my/i;
ignoreReg.test(testString);
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獲取匹配到的內容

• 獲取第一個匹配

const match = "My test string".match(/test/i);
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• 獲取全部匹配使用(g)

const match = "My test string,My regex will be better!".match(/my/ig);
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• 使用通配符(.)做爲任何字符的佔位符

const regexWithWildcard = /.at/gi;
const testString = "cat BAT cupcake AT mat dog";
const allMatchingWords = testString.match(regexWithWildcard);
//["cat", "BAT", " AT", "mat"]
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• 匹配具備多種可能性的單個字符，把它們放在([])中

const regexWithCharClass = /[cfm]at/g;
const testString = "cat fat bat mat";
const allMatchingWords = testString.match(regexWithCharClass);
//["cat", "fat", "mat"]
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• 匹配字母使用字符集範圍[a-z]

var regexWithCharRange = /[a-e]at/;
var catString = "cat";
var batString = "bat";
var fatString = "fat";
var cStr = catString.match(regexWithCharRange)
//["cat"]
var fStr = fatString.match(regexWithCharRange)
//null
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• 匹配特定字符和字母

var str = "hello, i am meteor, i am 12years old";
var regex = /[0-9a-z]/ig;
var rStr = regex.test(str);
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• 匹配單個未知字符，使用符號(^)

const regex = /[^aeiou]/gi;
var str = "how a beatuiful day it is!";
var match = str.match(regex);
//["h", "w", " ", " ", "b", "t", "f", "l", " ", "d", "y", " ", "t", " ", "s", "!"]
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• 匹配連續出現1次或屢次的字符，使用符號(+)

var regL = /l+/gi;
var regH = /h+/gi;
var str = "hello!how are you?";
var r1 = str.match(regL)    //["ll"]
var r2 = str.match(regH)    //["h", "h"]
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• 匹配連續出現0次或屢次的字符，使用符號(*)

var regex = /hi*/gi;
var normalHi = "Hi";
var happyHi = "hiiiiii";
var twoHi = "hiihii";
var normalResult = normalHi.match(regex);   //["Hi"]
var happyResult = happyHi.match(regex);     //["hiiiiii"]
var twoResult = twoHi.match(regex);         //["hii", "hii"]
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• 惰性匹配，使用符號(?)

var str = "catastrophe";
var regex = /c[a-z]*t/;
var regexLazy = /c[a-z]*?t/;
var result = str.match(regex)           //["catast"]
var resultLazy = str.match(regexLazy)   //["cat"]
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• 匹配起始字符串，使用符號(^)

var str1 = "how are you";
var str2 = "you are welcome";
var regex = /^you/ig;
var r1 = str1.match(regex)      //null
var r2 = str2.match(regex)      //["you"]
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• 匹配結束字符串，使用符號($)

var str1 = "how are you";
var str2 = "you are welcome";
var regex = /you$/ig;
var r1 = str1.match(regex)      //["you"]
var r2 = str2.match(regex)      //null
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• 匹配全部字母和數字，使用符號 word(\w)

var shortHand = /\w+/
var numbers = "0123456789";
var str = "abcdefghijklmn";
var rS = numbers.match(shortHand);  //"0123456789"
var rN = str.match(shortHand);      //"abcdefghijklmn"
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• 匹配除了字母和數字的全部內容,使用符號(\W)

var word = "123qwe";
var noWord = "!@#@#%#$";
var regex = /\W+/;
var rw = word.match(regex);         //null
var rwN = noWord.match(regex);      //["!@#@#%#$"]
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• 匹配全部數字，使用符號 digest(\d)

var str = "i am 23 years old";
var regex = /\d+/;
var result = str.match(regex)       //["23"]
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• 匹配全部非數字，使用符號(\D)

var str = "i am 23 years old";
var regex = /\D+/;
var result = str.match(regex)       //["i am "]
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• 匹配空格，使用符號(\s)

var str = "How are you?";
var regex = /\s+/g;
var result = str.match(regex)       //[" ", " "]
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• 匹配非空格，使用符號(\S)

var str = "How are you?";
var regex = /\S+/g;
var result = str.match(regex);      //["How", "are", "you?"]
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• 匹配字符數，匹配字符串中特定的字符數，使用符號({}) {lowerBound, upperBound}

var regularHi = "hi";
var mediocreHi = "hiii";
var superExcitedHey = "heeeeyyyyy!!!";
var excitedRegex = /hi{1,4}/;
var resultRegular = regularHi.match(excitedRegex);      // ["hi"]
var resultMediocre = mediocreHi.match(excitedRegex);    // ["hiii"]
var resultSuper = superExcitedHey.match(excitedRegex);  // null
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• 匹配至少字符數，使用({}) {lowerBound,}

var regularHi = "hi";
var mediocreHi = "hiii";
var superExcitedHey = "heeeeyyyyy!!!";
var excitedRegex = /hi{1,}/;

var resultRegular = regularHi.match(excitedRegex);      // ["hi"]
var resultMediocre = mediocreHi.match(excitedRegex);    // ["hiii"]
var resultSuper = superExcitedHey.match(excitedRegex);  // null
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• 匹配確切字符數，使用({}) {requiredCount}

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
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