正则表达式小括号的多义性正则表达式去掉括号正则表达式匹配括号正则表达式括号配

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var reg1 = /(Matz)?/; // 0或1个Matz

var reg2 = /(Matz)+/; // 1个以上Matz

var reg3 = /(Matz)*/; // 0或多个Matz

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var reg = /(Matz|Eich)/

reg.test('Matz') // => true

reg.test('Eich') // => true

reg.test('John') // => false

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var reg = /(boy)\1/ // 相当于 /boyboy/

reg.test('boy') // => false

reg.test('boyboy') // => true

var reg /(boy)(girl)\1\2/

reg.test('boygirlboygirl') // => true

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var reg1 = /(\d{3}) (\d{3})/

var str = '111 222'

str.replace(reg1, '$2 $1') // => '222 111' , 注意这里的$2,$1，存放了匹配的字符串

var reg2 = /(\d{3})(\d{4})(\d{4})/

var mobile = '13522722724'

reg2.test(mobile)

RegExp.$1 // => 135

RegExp.$2 // => 2272

RegExp.$3 // => 2724

var reg3 = /(\d{3})(\d{4})(\d{4})/

var mobile = '13522722724'

mobile.replace(reg3, '$1 $2 $3') // => '135 2272 2724'

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var reg = /(?:\d+)/

reg.test('13522722724')

RegExp.$1 // => '' 不存储匹配的元素

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var reg = /(John) (?=Resig)/

reg.test('John') // => false

reg.test('John Backus') // => false

reg.test('John Reisg') // => true

RegExp.$1 // => 'John'，注意这里不是 "John Resig"

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/*

* 手机号分隔

* 13522722724 -> 135 2272 2724

*/

function separateMobile(num) {

var arr = ( '0' + num ).replace(/(\d{4})(?=\d)/g,"$1 ").split('')

arr.shift()

return arr.join('')

}