>[success] # js 正則 ~~~ 1.正則表達式，又稱規則表達式。（英語：Regular Expression，在代碼中常簡寫為regex、regexp或RE）， 正則表達式通常被用來檢索、替換那些符合某個模式(規則)的文本。 2.用來匹配字符串 3.正則表達式的組成:是由元字符或者是限定符組成的一個式子 ~~~ >[danger] ##### 元字符   >[danger] ##### 字符集合  >[danger] ##### 量詞  >[danger] ##### 分支  >[danger] ##### 貪婪與懶惰 ~~~ 1.'貪婪模式'——在匹配成功的前提下，盡可能多的去匹配 2.'惰性模式'——在匹配成功的前提下，盡可能少的去匹配 說明:js 正則默認是貪婪模式,就是符合情況下盡可能多的去匹配 ~~~ ~~~ const str = 'I want you to (match the content) between the bracket)'; // 貪婪匹配只要滿足我都要 console.log(/((.*))/.exec(str)); // 惰性遇到? 問號的意思是滿足零次或者一次 也就是最少次數 // + 加號的意思是一次或者多次也就是 配合問號最少次數 則滿足一次即可 console.log(/((.+?))/.exec(str)); // 找到滿足非( 開始的字符以貪婪匹配則滿足的都要 console.log(/(([^(]*))/.exec(str)); // 找到滿足非( 開始的字符以惰性匹配則滿足即第一個滿足 console.log(/(([^(]+?))/.exec(str)); ~~~ * 輸出打印結果 ~~~ [ 'I want you to (match the content) between the bracket)', 'I want you to (match the content) between the bracket)', 'I want you to (match the content) between the bracket)', index: 0, input: 'I want you to (match the content) between the bracket)', groups: undefined ] [ 'I', 'I', 'I', index: 0, input: 'I want you to (match the content) between the bracket)', groups: undefined ] [ 'I want you to ', 'I want you to ', 'I want you to ', index: 0, input: 'I want you to (match the content) between the bracket)', groups: undefined ] [ 'I', 'I', 'I', index: 0, input: 'I want you to (match the content) between the bracket)', groups: undefined ] ~~~