正则表达式 目标 1 var web_development = "python php ruby javascript jsonp perhapsphpisoutdated";
找出其中包含p但不包含ph的所有单词,即[ 'python', 'javascript', 'jsonp']
知识点
正则表达式的使用
js中正则表达式与pcre 的区别
课程内容 开始这门课之前,先学习正则表达式30分钟入门教程 正则表达式之:零宽断言不『消费』
很久以前,处理字符串领域的王者当属perl.http://refiddle.com/,所见即所得地调试
讲述js中正则表达式
js中,对于四种零宽断言,只支持零宽正预测先行断言和零宽度负预测先行断言
js中,正则表达式后面可以跟三个flag.比如/something/igm.
i的意义是不区分大小写
g的意义是匹配多个
m的意义是^和$可以匹配每一行的开头
举几个例子:
1 2 3 4 5 6 /a/.test('A') // => false /a/i.test('A') // => true 'hello hell hoo'.match(/h.*?\b) // => [ 'hello', index: 0, input: 'hello hell hoo' ] 'hello hell hoo'.match(/h.*?\b/g) // => [ 'hello', 'hell', 'hoo' ] 'aaa\nbbb\nccc'.match(/^[\s\S)*?$/g) // => [ 'aaa\nbbb\nccc' ] 'aaa\nbbb\nccc'.match(/^[\s\S]*?$/gm) // => [ 'aaa', 'bbb', 'ccc' ]
还有一些别的:
1 2 3 \A 字符串开头(类似^,但不受处理多行选项的影响) \Z 字符串结尾或行尾(不受处理多行选项的影响) \z 字符串结尾(类似$,但不受处理多行选项的影响)
在js中,g flag 会影响String.prototype.match()和RegExp.prototype.exec()的行为String.prototype.match()中,返回数据的格式会不一样,加g会返回数组,不加g则返回比较详细的信息
1 2 'hello hell'.match(/h(.*?)\b/g) // => [ 'hello', 'hell' ] 'hello hell'.match(/h(.*?)\b/) // => [ 'hello', 'ello', index: 0, input: 'hello hell' ]
RegExp.prototype.exec()中:
1 2 3 4 5 /h(.*?)\b/g.exec('hello hell') // => [ 'hello', 'ello', index: 0, input: 'hello hell' ] /h(.*?)\b/g.exec('hello hell') // => [ 'hello', 'ello', index: 0, input: 'hello hell' ] var re = /h(.*?)\b/g; re.exec('hello hell') // => [ 'hello', 'ello', index: 0, input: 'hello hell' ] re.exec('hello hell') // => [ 'hell', 'ell', index: 6, input: 'hello hell' ]
第三.大家知道.是不可以匹配\n的.如果我们想匹配的数据涉及到了跨行:
1 2 3 4 5 6 7 8 9 10 var mutiline = require('multiline'); var text = multiline.stripIndent(function(){ /* head ``` code code2 .code3``` ``` foot */ });
如果需要获取两个1 2 3 4 5 6 7 8 惯用写法`[\s\S]` ``` code var match1 = text.match(/^```[\s\S]+?^```/gm); console.log(match1); //这里有一种很骚的写法,[^]与[\s\S]等价 var match2 = text.match(/^```[^]+?^```/gm); console.log(match2);
结果:
1 2 [ '```\ncode code2 .code3```\n```' ] [ '```\ncode code2 .code3```\n```' ]
我把学习中写的代码全贴上了,自己测试
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 var s = 'aaalllsss0tAAAnnn999'; var re2 = /(\w)\1{2}(?=(\w)\2{2})/g; console.log(s.match(re2)); var s = 'aaalllsss0tAAAnnn999'; var re1 = /((\w)\2{2})(\w)\3{2}/g; console.log(s.match(re1)); var s = 'aaalllsss0tAAAnnn999'; var re1 = /((\w)\2{2})(\w)\3{2}/g; console.log("s is: " + s); console.log(); var res; while(res=re1.exec(s)) { console.log("match result: " + res[1] + ".", "re1 comsumed: " + res[0], "re1.lastindex: " + re1.lastIndex, "remain string: " + s.slice(re1.lastIndex)); } var s = 'aaalllsss0tAAAnnn999'; var re1 = /(\w)\1{2}(?=(\w)\2{2})/g; console.log("s is: " + s); console.log(); var res; while(res=re1.exec(s)) { console.log("match result: " + res[1] + ".", "re1 comsumed: " + res[0], "re1.lastindex: " + re1.lastIndex, "remain string: " + s.slice(re1.lastIndex)); } console.log(/a/.test('A')); console.log(/a/i.test('A')); console.log('hello hell hoo'.match(/h.*?\b/)); console.log('hello hell hoo'.match(/h.*?\b/g)); console.log('aaa\nbbb\nccc'.match(/^[\s\S]*?$/g)); console.log('aaa\nbbb\nccc'.match(/^[\s\S]*?$/gm)); console.log('hello hell'.match(/h(.*?)\b/g)); console.log('hello hell'.match(/h(.*?)\b/)); console.log(/h(.*?)\b/g.exec('hello hell')); console.log(/h(.*?)\b/g.exec('hello hell')); var re = /h(.*?)\b/g; console.log(re.exec('hello hell')); console.log(re.exec('hello hell')); var multiline = require('multiline'); var text = multiline.stripIndent(function(){ /* head ``` code code2 .code3``` ``` foot */ }); var match1 = text.match(/^```[\s\S]+?^```/gm); console.log(match1); //这里有一种很骚的写法,[^]与[\s\S]等价 var match2 = text.match(/^```[^]+?^```/gm); console.log(match2);
目标答案,出自一个牛人之手,我写了好久都没写出来…-_-!!!
1 2 3 4 5 6 7 8 9 10 11 var web_development = 'python php ruby javascript jsonp perhapsphpisoutdated'; var reg1 = /\b(?=\w*p\w*)(?!\w*ph\w*)\w*\b/ig; console.log("web_development is: " + web_development); console.log(web_development.match(reg1)); var res; while(res = reg1.exec(web_development)) { console.log("match result: " + res[1] + ".", "reg1 comsumed: " + res[0], "reg1.lastindex: " + reg1.lastIndex, "remain string: " + web_development.slice(reg1.lastIndex)); }
