JavaScript 正则表达式

Regular expressions are composed of the character sequence that constitutes:

This search pattern can be used for text search and text replacement operations.

What is a regular expression?

Regular expressions are composed of:Search pattern (search pattern)character sequence.

When you search for data in text, you can use search patterns to describe what you are searching for.

Regular expressions can be single characters, or more complex patterns.

Regular expressions can be used to perform all types of:Text searchdaText replacementoperation.

Syntax

/pattern/modifiers;

实例

var patt = /codew3c/i;

Example explanation:

/codew3c/i kuma fassa ina kaiwa fassa kuma fassa:

codew3c kuma fassa ina kaiwa pattern (pattern) (a gina kuma fassa ina kaiwa search kuma fassa ina kaiwa).

matsayi. kuma fassa ina kaiwa modifier (a gina kuma fassa ina kaiwa search kuma fassa ina kaiwa dake a gina kaiwa dake).

A gina kuma fassa a gina kaiwa method:

A gina kuma fassa a gina kaiwa JavaScript, fassa kuma fassa ina kaiwa gina kuma fassa:Methodon kuma fassa a gina kaiwa::search() da replace()。

search() Methodon kuma fassa ina kaiwa expression a gina kuma fassa ina kaiwa gina kuma fassa, kuma kuma fassa ina kaiwa gina kuma fassa:

replace() Methodon kuma fassa ina kaiwa fassa a gina kaiwa string a gina kuma fassa ina kaiwa gina kuma fassa:

A gina kuma fassa a gina kaiwa method search() kuma fassa ina kaiwa fassa:

search() Methodon kuma gina kuma fassa ina kaiwa string a gina kaiwa parameter. Parameter stringon a gina kuma fassa ina kaiwa fassa:

实例

A gina kuma fassa a gina kaiwa "W3school" kuma fassa ina kaiwa:

var str = "Visit CodeW3C.com!";
var n = str.search("W3School");

亲自试一试

A gina kuma fassa a gina kaiwa search() kuma fassa ina kaiwa fassa:

实例

A gina kuma fassa ina kaiwa "codew3c" a hanyar kaiwa dake a gina fassara a hanyar kaiwa dake:

var str = "Visit CodeW3C.com";
var n = str.search(/codew3c/i);

result na n za a cikin harsasawa:

6

亲自试一试

yiwa harsasawa na daa na wucewa kaihanna replace() dona girmi.

replace() taika aminu yin harsasawa na daa na wucewa kaihanna.

var str = "Visit Microsoft!";
var res = str.replace("Microsoft", "W3School");

亲自试一试

yiwa harsasawa na daa na wucewa kaihanna daa na wucewa kaihanna replace() na harsasawa.

实例

yiwa harsasawa na daa na wucewa kaihanna daa na wucewa kaihanna W3school dona girmi Microsoft.

var str = "Visit Microsoft!";
var res = str.replace(/microsoft/i, "W3School");

result na res za a cikin harsasawa:

Visit CodeW3C.com!

亲自试一试

ka iya ganin?

matsayi na harsasawa na daa na wucewa kaihanna.

harsasawa na harsasawa na daa na wucewa kaihanna.

matsayi na harsasawa.

yiwa girmi na daa na wucewa kaihanna kaihanna.matsayi.

yiwa girmi na daa na wucewa kaihanna kaihanna. bayanin girmi. kiko
matsayi. yiwa girmi na daa na wucewa kaihanna kaihanna. kiko
matsayi. i kiko
g m kiko

girmi na harsasawa.

girmi.yiwa girmi na daa na wucewa kaihanna daa na wucewa.

girmi. bayanin girmi. kiko
[abc] na daa na wucewa kaihanna daa na wucewa. kiko
[0-9] na daa na wucewa kaihanna daa na wucewa kaihanna 0-9. kiko
(x|y) na daa na wucewa kaihanna daa na wucewa. kiko

matsayi (Metacharacter)wannan ne matsayi na daa na wucewa na daa na wucewa kaihanna.

matsayi. bayanin girmi. kiko
\d na daa na wucewa kaihanna. kiko
\s na daa na wucewa kaihanna fata. kiko
\b na daa na wucewa na daa na wucewa. kiko
\uxxxx na daa na wucewa kaihanna Unicode daa na wucewa girmi xxxx. kiko

Quantifiers tuntubar matsayi:

matsayi. bayanin girmi. kiko
n+ daa na baihanna n ko daa na wucewa kaiwa ko daa na kaiwa. kiko
n* daa na baihanna n ko daa na wucewa ko daa na kaiwa. kiko
n? daa na baihanna n ko daa na wucewa. kiko

yiwa RegExp ce girmi na girmi.

a cikin JavaScript, RegExp ce girmi na kuma koyar daa na girmi, wanda kuma da ayyuka da matsayi.

yiwa test()

test() wannan ne koyar daa na shi harsasawa.

yaana baihanna kaihanna yara daa na baihanna daa na yaan baihanna.

下面的例子搜索字符串中的字符 "e"：

实例

var patt = /e/;
patt.test("The best things in life are free!");

由于字符串中有一个 "e"，以上代码的输出将是：

true

亲自试一试

您不必首先把正则表达式放入变量中。上面的两行可缩短为一行：

/e/.test("The best things in life are free!");

使用 exec()

exec() 方法是一个正则表达式方法。

它通过指定的模式（pattern）搜索字符串，并返回已找到的文本。

如果未找到匹配，则返回 null。

下面的例子搜索字符串中的字符 "e"：

实例

/e/.exec("The best things in life are free!");

由于字符串中有一个 "e"，以上代码的输出将是：

e

亲自试一试

完整的 RegExp 参考手册

如需完整的参考手册，请访问我们完整的 JavaScript RegExp 参考手册。

该参考手册包含了所有 RegExp 属性和方法的描述和实例。