| 1 |
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"),t("p",[t("code",[s._v("y")]),s._v("修饰符同样遵守"),t("code",[s._v("lastIndex")]),s._v("属性，但是要求必须在"),t("code",[s._v("lastIndex")]),s._v("指定的位置发现匹配。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("REGEX")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("a")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-flags"}},[s._v("y")])]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 指定从2号位置开始匹配")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("REGEX")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),s._v("lastIndex "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token number"}},[s._v("2")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 不是粘连，匹配失败")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("REGEX")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("exec")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'xaya'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// null")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 指定从3号位置开始匹配")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("REGEX")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),s._v("lastIndex "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token number"}},[s._v("3")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 3号位置是粘连，匹配成功")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" match "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("REGEX")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("exec")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token 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"),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("b")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-flags"}},[s._v("y")])]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("exec")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'aba'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// null")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br")])]),t("p",[s._v("上面代码由于不能保证头部匹配，所以返回"),t("code",[s._v("null")]),s._v("。"),t("code",[s._v("y")]),s._v("修饰符的设计本意，就是让头部匹配的标志"),t("code",[s._v("^")]),s._v("在全局匹配中都有效。")]),s._v(" "),t("p",[s._v("下面是字符串对象的"),t("code",[s._v("replace")]),s._v("方法的例子。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("REGEX")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source 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punctuation"}},[s._v("(")]),s._v("\\d"),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("+")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v("$"),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("exec")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'1053'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v('// ["1053", "105", "3"]')]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br")])]),t("p",[s._v("上面代码中，需要捕捉两个组匹配。没有“后行断言”时，第一个括号是贪婪模式，第二个括号只能捕获一个字符，所以结果是"),t("code",[s._v("105")]),s._v("和"),t("code",[s._v("3")]),s._v("。而“后行断言”时，由于执行顺序是从右到左，第二个括号是贪婪模式，第一个括号只能捕获一个字符，所以结果是"),t("code",[s._v("1")]),s._v("和"),t("code",[s._v("053")]),s._v("。")]),s._v(" "),t("p",[s._v("其次，“后行断言”的反斜杠引用，也与通常的顺序相反，必须放在对应的那个括号之前。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("(?<=(o)d\\1)r")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")])]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("exec")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'hodor'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// null")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("?")]),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("<=")]),s._v("\\"),t("span",{pre:!0,attrs:{class:"token number"}},[s._v("1")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("d")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),s._v("o"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v("r"),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("exec")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'hodor'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v('// ["r", "o"]')]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br")])]),t("p",[s._v("上面代码中，如果后行断言的反斜杠引用（"),t("code",[s._v("\\1")]),s._v("）放在括号的后面，就不会得到匹配结果，必须放在前面才可以。因为后行断言是先从左到右扫描，发现匹配以后再回过头，从右到左完成反斜杠引用。")]),s._v(" "),t("h2",{attrs:{id:"unicode-属性类"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#unicode-属性类"}},[s._v("#")]),s._v(" Unicode 属性类")]),s._v(" "),t("p",[s._v("ES2018 "),t("a",{attrs:{href:"https://github.com/tc39/proposal-regexp-unicode-property-escapes",target:"_blank",rel:"noopener noreferrer"}},[s._v("引入"),t("OutboundLink")],1),s._v("了一种新的类的写法"),t("code",[s._v("\\p{...}")]),s._v("和"),t("code",[s._v("\\P{...}")]),s._v("，允许正则表达式匹配符合 Unicode 某种属性的所有字符。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" regexGreekSymbol "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("\\p{Script=Greek}")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-flags"}},[s._v("u")])]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\nregexGreekSymbol"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("test")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'π'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// true")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br")])]),t("p",[s._v("上面代码中，"),t("code",[s._v("\\p{Script=Greek}")]),s._v("指定匹配一个希腊文字母，所以匹配"),t("code",[s._v("π")]),s._v("成功。")]),s._v(" "),t("p",[s._v("Unicode 属性类要指定属性名和属性值。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("UnicodePropertyName"),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v("UnicodePropertyValue"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br")])]),t("p",[s._v("对于某些属性，可以只写属性名，或者只写属性值。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("UnicodePropertyName"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\n\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("UnicodePropertyValue"),t("span",{pre:!0,attrs:{class:"token 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"),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br")])]),t("p",[s._v("上面代码中，属性类指定匹配所有十进制字符，可以看到各种字型的十进制字符都会匹配成功。")]),s._v(" "),t("p",[t("code",[s._v("\\p{Number}")]),s._v("甚至能匹配罗马数字。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 匹配所有数字")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" regex "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("^\\p{Number}+$")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-flags"}},[s._v("u")])]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\nregex"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("test")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'²³¹¼½¾'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// true")]),s._v("\nregex"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("test")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'㉛㉜㉝'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// true")]),s._v("\nregex"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("test")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'ⅠⅡⅢⅣⅤⅥⅦⅧⅨⅩⅪⅫ'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// true")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br")])]),t("p",[s._v("下面是其他一些例子。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 匹配所有空格")]),s._v("\n\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("White_Space"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 匹配各种文字的所有字母，等同于 Unicode 版的 \\w")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("[")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Alphabetic"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Mark"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Decimal_Number"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Connector_Punctuation"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Join_Control"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("]")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 匹配各种文字的所有非字母的字符，等同于 Unicode 版的 \\W")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("[")]),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("^")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Alphabetic"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Mark"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Decimal_Number"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Connector_Punctuation"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Join_Control"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("]")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 匹配 Emoji")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("/")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Emoji_Modifier_Base"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Emoji_Modifier"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("?")]),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("|")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Emoji_Presentation"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("|")]),s._v("\\p"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("Emoji"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\\uFE0F"),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("/")]),s._v("gu\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 匹配所有的箭头字符")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" regexArrows "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("^\\p{Block=Arrows}+$")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-flags"}},[s._v("u")])]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\nregexArrows"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("test")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'←↑→↓↔↕↖↗↘↙⇏⇐⇑⇒⇓⇔⇕⇖⇗⇘⇙⇧⇩'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// true")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br"),t("span",{staticClass:"line-number"},[s._v("6")]),t("br"),t("span",{staticClass:"line-number"},[s._v("7")]),t("br"),t("span",{staticClass:"line-number"},[s._v("8")]),t("br"),t("span",{staticClass:"line-number"},[s._v("9")]),t("br"),t("span",{staticClass:"line-number"},[s._v("10")]),t("br"),t("span",{staticClass:"line-number"},[s._v("11")]),t("br"),t("span",{staticClass:"line-number"},[s._v("12")]),t("br"),t("span",{staticClass:"line-number"},[s._v("13")]),t("br"),t("span",{staticClass:"line-number"},[s._v("14")]),t("br"),t("span",{staticClass:"line-number"},[s._v("15")]),t("br")])]),t("h2",{attrs:{id:"具名组匹配"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#具名组匹配"}},[s._v("#")]),s._v(" 具名组匹配")]),s._v(" "),t("h3",{attrs:{id:"简介"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#简介"}},[s._v("#")]),s._v(" 简介")]),s._v(" "),t("p",[s._v("正则表达式使用圆括号进行组匹配。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("RE_DATE")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("(\\d{4})-(\\d{2})-(\\d{2})")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")])]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n")])]),s._v(" 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"),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br"),t("span",{staticClass:"line-number"},[s._v("6")]),t("br")])]),t("p",[s._v("上面代码中，“具名组匹配”在圆括号内部，模式的头部添加“问号 + 尖括号 + 组名”（"),t("code",[s._v("?<year>")]),s._v("），然后就可以在"),t("code",[s._v("exec")]),s._v("方法返回结果的"),t("code",[s._v("groups")]),s._v("属性上引用该组名。同时，数字序号（"),t("code",[s._v("matchObj[1]")]),s._v("）依然有效。")]),s._v(" "),t("p",[s._v("具名组匹配等于为每一组匹配加上了 ID，便于描述匹配的目的。如果组的顺序变了，也不用改变匹配后的处理代码。")]),s._v(" "),t("p",[s._v("如果具名组没有匹配，那么对应的"),t("code",[s._v("groups")]),s._v("对象属性会是"),t("code",[s._v("undefined")]),s._v("。")]),s._v(" "),t("div",{staticClass:"language-javascript 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"),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br")])]),t("p",[s._v("上面代码中，具名组"),t("code",[s._v("as")]),s._v("没有找到匹配，那么"),t("code",[s._v("matchObj.groups.as")]),s._v("属性值就是"),t("code",[s._v("undefined")]),s._v("，并且"),t("code",[s._v("as")]),s._v("这个键名在"),t("code",[s._v("groups")]),s._v("是始终存在的。")]),s._v(" "),t("h3",{attrs:{id:"解构赋值和替换"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#解构赋值和替换"}},[s._v("#")]),s._v(" 解构赋值和替换")]),s._v(" "),t("p",[s._v("有了具名组匹配以后，可以使用解构赋值直接从匹配结果上为变量赋值。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("let")]),s._v(" 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line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("let")]),s._v(" re "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("(?<year>\\d{4})-(?<month>\\d{2})-(?<day>\\d{2})")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-flags"}},[s._v("u")])]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'2015-01-02'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("replace")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),s._v("re"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(",")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'$<day>/$<month>/$<year>'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// '02/01/2015'")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br")])]),t("p",[s._v("上面代码中，"),t("code",[s._v("replace")]),s._v("方法的第二个参数是一个字符串，而不是正则表达式。")]),s._v(" "),t("p",[t("code",[s._v("replace")]),s._v("方法的第二个参数也可以是函数，该函数的参数序列如下。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'2015-01-02'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("replace")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),s._v("re"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(",")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),s._v("\n matched"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(",")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 整个匹配结果 2015-01-02")]),s._v("\n capture1"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(",")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 第一个组匹配 2015")]),s._v("\n capture2"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(",")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 第二个组匹配 01")]),s._v("\n capture3"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(",")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 第三个组匹配 02")]),s._v("\n position"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(",")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 匹配开始的位置 0")]),s._v("\n "),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("S")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(",")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 原字符串 2015-01-02")]),s._v("\n groups "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 具名组构成的一个对象 {year, month, day}")]),s._v("\n "),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=>")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("\n "),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("let")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("day"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(",")]),s._v(" month"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(",")]),s._v(" year"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" groups"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n "),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("return")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token template-string"}},[t("span",{pre:!0,attrs:{class:"token template-punctuation string"}},[s._v("`")]),t("span",{pre:!0,attrs:{class:"token interpolation"}},[t("span",{pre:!0,attrs:{class:"token interpolation-punctuation punctuation"}},[s._v("${")]),s._v("day"),t("span",{pre:!0,attrs:{class:"token interpolation-punctuation punctuation"}},[s._v("}")])]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token 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"),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br"),t("span",{staticClass:"line-number"},[s._v("6")]),t("br"),t("span",{staticClass:"line-number"},[s._v("7")]),t("br"),t("span",{staticClass:"line-number"},[s._v("8")]),t("br"),t("span",{staticClass:"line-number"},[s._v("9")]),t("br"),t("span",{staticClass:"line-number"},[s._v("10")]),t("br"),t("span",{staticClass:"line-number"},[s._v("11")]),t("br"),t("span",{staticClass:"line-number"},[s._v("12")]),t("br")])]),t("p",[s._v("具名组匹配在原来的基础上，新增了最后一个函数参数：具名组构成的一个对象。函数内部可以直接对这个对象进行解构赋值。")]),s._v(" "),t("h3",{attrs:{id:"引用"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#引用"}},[s._v("#")]),s._v(" 引用")]),s._v(" "),t("p",[s._v("如果要在正则表达式内部引用某个“具名组匹配”，可以使用"),t("code",[s._v("\\k<组名>")]),s._v("的写法。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("RE_TWICE")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("^(?<word>[a-z]+)!\\k<word>$")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")])]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("RE_TWICE")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("test")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'abc!abc'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// true")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("RE_TWICE")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("test")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'abc!ab'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// false")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br")])]),t("p",[s._v("数字引用（"),t("code",[s._v("\\1")]),s._v("）依然有效。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("RE_TWICE")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("^(?<word>[a-z]+)!\\1$")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")])]),t("span",{pre:!0,attrs:{class:"token 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false")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br")])]),t("p",[s._v("这两种引用语法还可以同时使用。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token constant"}},[s._v("RE_TWICE")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("^(?<word>[a-z]+)!\\k<word>!\\1$")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")])]),t("span",{pre:!0,attrs:{class:"token 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false")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br")])]),t("h2",{attrs:{id:"string-prototype-matchall"}},[t("a",{staticClass:"header-anchor",attrs:{href:"#string-prototype-matchall"}},[s._v("#")]),s._v(" String.prototype.matchAll()")]),s._v(" "),t("p",[s._v("如果一个正则表达式在字符串里面有多个匹配，现在一般使用"),t("code",[s._v("g")]),s._v("修饰符或"),t("code",[s._v("y")]),s._v("修饰符，在循环里面逐一取出。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("var")]),s._v(" regex "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token 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function"}},[s._v("push")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),s._v("match"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\n\nmatches\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// [")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v('// ["test1", "e", "st1", "1", index: 0, input: "test1test2test3"],')]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v('// ["test2", "e", "st2", "2", index: 5, input: "test1test2test3"],')]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v('// ["test3", "e", "st3", "3", index: 10, input: "test1test2test3"]')]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// ]")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br"),t("span",{staticClass:"line-number"},[s._v("6")]),t("br"),t("span",{staticClass:"line-number"},[s._v("7")]),t("br"),t("span",{staticClass:"line-number"},[s._v("8")]),t("br"),t("span",{staticClass:"line-number"},[s._v("9")]),t("br"),t("span",{staticClass:"line-number"},[s._v("10")]),t("br"),t("span",{staticClass:"line-number"},[s._v("11")]),t("br"),t("span",{staticClass:"line-number"},[s._v("12")]),t("br"),t("span",{staticClass:"line-number"},[s._v("13")]),t("br"),t("span",{staticClass:"line-number"},[s._v("14")]),t("br"),t("span",{staticClass:"line-number"},[s._v("15")]),t("br")])]),t("p",[s._v("上面代码中，"),t("code",[s._v("while")]),s._v("循环取出每一轮的正则匹配，一共三轮。")]),s._v(" "),t("p",[t("a",{attrs:{href:"https://github.com/tc39/proposal-string-matchall",target:"_blank",rel:"noopener noreferrer"}},[s._v("ES2020"),t("OutboundLink")],1),s._v(" 增加了"),t("code",[s._v("String.prototype.matchAll()")]),s._v("方法，可以一次性取出所有匹配。不过，它返回的是一个遍历器（Iterator），而不是数组。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" string "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token string"}},[s._v("'test1test2test3'")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// g 修饰符加不加都可以")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" regex "),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("=")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token regex"}},[t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-source language-regex"}},[s._v("t(e)(st(\\d?))")]),t("span",{pre:!0,attrs:{class:"token regex-delimiter"}},[s._v("/")]),t("span",{pre:!0,attrs:{class:"token regex-flags"}},[s._v("g")])]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("for")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("const")]),s._v(" match "),t("span",{pre:!0,attrs:{class:"token keyword"}},[s._v("of")]),s._v(" string"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("matchAll")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),s._v("regex"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v(" "),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("{")]),s._v("\n console"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("log")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),s._v("match"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(";")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("}")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v('// ["test1", "e", "st1", "1", index: 0, input: "test1test2test3"]')]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v('// ["test2", "e", "st2", "2", index: 5, input: "test1test2test3"]')]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v('// ["test3", "e", "st3", "3", index: 10, input: "test1test2test3"]')]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br"),t("span",{staticClass:"line-number"},[s._v("6")]),t("br"),t("span",{staticClass:"line-number"},[s._v("7")]),t("br"),t("span",{staticClass:"line-number"},[s._v("8")]),t("br"),t("span",{staticClass:"line-number"},[s._v("9")]),t("br"),t("span",{staticClass:"line-number"},[s._v("10")]),t("br"),t("span",{staticClass:"line-number"},[s._v("11")]),t("br")])]),t("p",[s._v("上面代码中，由于"),t("code",[s._v("string.matchAll(regex)")]),s._v("返回的是遍历器，所以可以用"),t("code",[s._v("for...of")]),s._v("循环取出。相对于返回数组，返回遍历器的好处在于，如果匹配结果是一个很大的数组，那么遍历器比较节省资源。")]),s._v(" "),t("p",[s._v("遍历器转为数组是非常简单的，使用"),t("code",[s._v("...")]),s._v("运算符和"),t("code",[s._v("Array.from()")]),s._v("方法就可以了。")]),s._v(" "),t("div",{staticClass:"language-javascript line-numbers-mode"},[t("pre",{pre:!0,attrs:{class:"language-javascript"}},[t("code",[t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 转为数组方法一")]),s._v("\n"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("[")]),t("span",{pre:!0,attrs:{class:"token operator"}},[s._v("...")]),s._v("string"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("matchAll")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),s._v("regex"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("]")]),s._v("\n\n"),t("span",{pre:!0,attrs:{class:"token comment"}},[s._v("// 转为数组方法二")]),s._v("\nArray"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("from")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),s._v("string"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(".")]),t("span",{pre:!0,attrs:{class:"token function"}},[s._v("matchAll")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v("(")]),s._v("regex"),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),t("span",{pre:!0,attrs:{class:"token punctuation"}},[s._v(")")]),s._v("\n")])]),s._v(" "),t("div",{staticClass:"line-numbers-wrapper"},[t("span",{staticClass:"line-number"},[s._v("1")]),t("br"),t("span",{staticClass:"line-number"},[s._v("2")]),t("br"),t("span",{staticClass:"line-number"},[s._v("3")]),t("br"),t("span",{staticClass:"line-number"},[s._v("4")]),t("br"),t("span",{staticClass:"line-number"},[s._v("5")]),t("br")])])])}),[],!1,null,null,null);t.default=n.exports}}]);
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