理顺 JavaScript (20) - String 中的正则表达式函数
search : 找到返回位置; 找不到返回 -1
var str, p, n; str = '1:abc;2:Abc;3:aBc;4:abC;5:ABc;6:aBC;7:AbC;8:ABC'; p = /abc/i; n = str.search(p); alert(n); //2 p = /abcde/i; n = str.search(p); alert(n); //-1 //这个函数和 RegExp.test 差不多, 不过 test 返回的是 true/false; 全局选项 g 对它们都没有意义.
match : 匹配并返回结果, 结果是数组
//首先, String.match 和 RegExp.exec 功能类似, 但 match 更方便使用. var str, p, arr; str = '1:abc;2:Abc;3:aBc;4:abC;5:ABc;6:aBC;7:AbC;8:ABC'; //不指定全局匹配, 只返回第一组(包含子匹配) p = /(ab)(c)/i; arr = str.match(p); alert(arr); //abc,ab,c //指定了全局匹配, 会返回所有匹配结果(但不包括子匹配) p = /(ab)(c)/ig; arr = str.match(p); alert(arr); //abc,Abc,aBc,abC,ABc,aBC,AbC,ABC //这个使用虽然方便了, 但不能获取所有子匹配的细节; 但 exec 可以.
replace : 强大的替换函数; replace(正则表达式, 要替换的内容); 返回替换后的结果
var str1, str2, p; str1 = '1:abc;2:Abc;3:aBc;4:abC;5:ABc;6:aBC;7:AbC;8:ABC'; p = /abc/ig; str2 = str1.replace(p, '*'); alert(str2); //1:*;2:*;3:*;4:*;5:*;6:*;7:*;8:* p = /abc/i; str2 = str1.replace(p, '*'); alert(str2); //1:*;2:Abc;3:aBc;4:abC;5:ABc;6:aBC;7:AbC;8:ABC //$1...$99 表示子表达式: var str1, str2, p; str1 = '1:abc;2:Abc;3:aBc;4:abC;5:ABc;6:aBC;7:AbC;8:ABC'; p = /(ab)(c)/ig; str2 = str1.replace(p, '$1'); alert(str2); //1:ab;2:Ab;3:aB;4:ab;5:AB;6:aB;7:Ab;8:AB p = /(ab)(c)/ig; str2 = str1.replace(p, '《$2》'); alert(str2); //1:《c》;2:《c》;3:《c》;4:《C》;5:《c》;6:《C》;7:《C》;8:《C》 //$& 表示整个表达式的匹配结果 var str1, str2, p; str1 = '1:abc;2:Abc;3:aBc;4:abC;5:ABc;6:aBC;7:AbC;8:ABC'; p = /(ab)(c)/ig; str2 = str1.replace(p, '"$&"'); alert(str2); //1:"abc";2:"Abc";3:"aBc";4:"abC";5:"ABc";6:"aBC";7:"AbC";8:"ABC" //$` 表示匹配结果左边的内容; $' 表示匹配结果右边的内容; $ 自身得用 $$ 表示. var str1, str2, p; str1 = '1234ABC5678'; p = /ABC/; str2 = str1.replace(p, '《$`》'); alert(str2); //1234《1234》5678 str2 = str1.replace(p, "《$'》"); alert(str2); //1234《5678》5678 str2 = str1.replace(p, '$$'); alert(str2); //1234$5678 //replace 的第二个参数可以是个函数(注意函数的调用方式有点特别) var str1, str2, p; str1 = '1:abc;2:Abc;3:aBc;4:abC;5:ABc;6:aBC;7:AbC;8:ABC'; p = /(ab)(c)/ig; function fun1(s) { return s.toUpperCase();} function fun2(s) { return '《' + s.toLowerCase() + '》';} function fun3(s) { return s.length;} str2 = str1.replace(p, fun1); alert(str2); //1:ABC;2:ABC;3:ABC;4:ABC;5:ABC;6:ABC;7:ABC;8:ABC str2 = str1.replace(p, fun2); alert(str2); //1:《abc》;2:《abc》;3:《abc》;4:《abc》;5:《abc》;6:《abc》;7:《abc》;8:《abc》 str2 = str1.replace(p, fun3); alert(str2); //1:3;2:3;3:3;4:3;5:3;6:3;7:3;8:3
split : 分割字符串, 返回数组
var str1, arr, p; str1 = '1:abc;2:Abc;3:aBc;4:abC;5:ABc;6:aBC;7:AbC;8:ABC'; p = /abc/i; arr = str1.split(p); alert(arr); //1:,;2:,;3:,;4:,;5:,;6:,;7:,;8: p = /;/; arr = str1.split(p); alert(arr); //1:abc,2:Abc,3:aBc,4:abC,5:ABc,6:aBC,7:AbC,8:ABC p = /;\d:/; arr = str1.split(p); alert(arr); //1:abc,Abc,aBc,abC,ABc,aBC,AbC,ABC
简单使用这几个函数
//如果在正则表达式的位置给了字符串, JavaScript 也会把它们转成正则表达式; 但不使用正则功能太弱了. var str1, str2, n, arr; str1 = 'Delphi 2009'; n = str1.search('p'); alert(n); //3 arr = str1.match('p'); alert(arr); //p str2 = str1.replace('0', '*'); alert(str2); //Delphi 2*09 arr = str1.split(' '); alert(arr[0]); //Delphi alert(arr[1]); //2009