第九周作業 regular expression rules 正則表示式
阿新 • • 發佈：2018-12-27
regular expression rules 正則表示式
正則表示式是用於匹配字串中字元組合的模式。在 JavaScript中，正則表示式也是物件。這些模式被用於 RegExp 的 exec 和 test 方法, 以及 String 的 match、replace、search 和 split 方法。本章介紹 JavaScript正則表示式。
建立一個正則表示式
1、使用一個正則表示式字面量，其由包含在斜槓之間的模式組成，如下所示：
| 1 2 3 4 5 6 7 |
<code class
=
" language-js"
><span
class
=
"token comment"
>
/*
/pattern/flags
*/
<span class
=
"token keyword"
>const regex <span
class
=
"token operator"
>= <span
class
=
"token regex"
>/ab+c/<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>const regex <span
class
=
"token operator"
>= <span
class
=
"token regex"
>/^[a-zA-Z]+[0-9]*\W?_$/gi<span
class
=
"token punctuation"
>;</span></span></span></span></span></span></span></span></span></code>在載入指令碼後，正則表示式字面值提供正則表示式的編譯。當正則表示式保持不變時，使用此方法可獲得更好的效能。<br><br>2、呼叫<code><a title=
"zh-CN/docs/JavaScript/Reference/Global Objects/RegExp"
href=
"https://developer.mozilla.org/zh-CN/docs/JavaScript/Reference/Global_Objects/RegExp"
>RegExp</a></code>物件的建構函式
|
| 1 2 3 4 5 6 7 8 9 |
<code
class
=
" language-js"
><span
class
=
"token comment"
>
/*
new RegExp(pattern [, flags])
*/
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token string"
>
"ab+c"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token regex"
>/^[a-zA-Z]+[0-9]*\W?_$/<span
class
=
"token punctuation"
>, <span
class
=
"token string"
>
"gi"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token string"
>
"^[a-zA-Z]+[0-9]*\\W?_$"
<span
class
=
"token punctuation"
>, <span
class
=
"token string"
>
"gi"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;<br><br></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></code>
|
正則表示式是用於匹配字串中字元組合的模式。在 JavaScript中，正則表示式也是物件。這些模式被用於 RegExp 的 exec 和 test 方法, 以及 String 的 match、replace、search 和 split 方法。本章介紹 JavaScript正則表示式。
建立一個正則表示式
1、使用一個正則表示式字面量，其由包含在斜槓之間的模式組成，如下所示：
| 1 2 3 4 5 6 7 |
<code
class
=
" language-js"
><span
class
=
"token comment"
>
/*
/pattern/flags
*/
<span
class
=
"token keyword"
>const regex <span
class
=
"token operator"
>= <span
class
=
"token regex"
>/ab+c/<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>const regex <span
class
=
"token operator"
>= <span
class
=
"token regex"
>/^[a-zA-Z]+[0-9]*\W?_$/gi<span
class
=
"token punctuation"
>;</span></span></span></span></span></span></span></span></span></code>在載入指令碼後，正則表示式字面值提供正則表示式的編譯。當正則表示式保持不變時，使用此方法可獲得更好的效能。<br><br>2、呼叫<code><a title=
"zh-CN/docs/JavaScript/Reference/Global Objects/RegExp"
href=
"https://developer.mozilla.org/zh-CN/docs/JavaScript/Reference/Global_Objects/RegExp"
>RegExp</a></code>物件的建構函式
|
| 1 2 3 4 5 6 7 8 9 |
<code
class
=
" language-js"
><span
class
=
"token comment"
>
/*
new RegExp(pattern [, flags])
*/
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token string"
>
"ab+c"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token regex"
>/^[a-zA-Z]+[0-9]*\W?_$/<span
class
=
"token punctuation"
>, <span
class
=
"token string"
>
"gi"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;
<span
class
=
"token keyword"
>
let
regex <span
class
=
"token operator"
>= <span
class
=
"token keyword"
>
new
<span
class
=
"token class-name"
>RegExp<span
class
=
"token punctuation"
>(<span
class
=
"token string"
>
"^[a-zA-Z]+[0-9]*\\W?_$"
<span
class
=
"token punctuation"
>, <span
class
=
"token string"
>
"gi"
<span
class
=
"token punctuation"
>)<span
class
=
"token punctuation"
>;<br><br></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></code>
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