Sharing the 12 most commonly used regular expressions can solve most of your problems

english | https://medium.com/frontend-canteen/you-dont-need-to-fully-understand-regex-you-just-need-to-know-these-10-most-used-expressions-197dd2397308

translate | Yang Xiaoai

To be frank , I have never understood regular expressions , I spent a lot of time learning it , But I still don't understand .

Later I learned a truth ： I really don't need to fully understand all the principles of regular expressions , Understand some common regular expressions thoroughly , Because the number of regular expressions we really use is limited , I just need to add them to my notebook （ You don't even need to remember ）.

today , I collected some web Regular expressions often used in projects , I think it can be solved 50% The above regular expression problem .

Digital

01、 Match only numeric strings

The goal is ：

12312
1232121
4353

Regular expressions ：

/^\d+$/

Simple explanation ：

• ^ Represents the beginning of a string

• \d+ Match one or more digits

• $ Represents the end of the string

visualization ：

usage ：

• 234,124 Contains illegal characters , , So it goes back to false.

• id12313 Contains two illegal characters id , So it goes back to false.

02、 Decimal number

The goal is ：

123.123
11
3.14
0.43
0
66
123

Regular expressions ：

/^\d+(\.?\d+)?$/

• \. Match a single char .

• ? Said the optional .

• () Represents a group

• (\.?\d)? Is an optional group

visualization ：

usage ：

. It should be in the middle of the number , therefore .1 and 12. return false.

03、 Alphanumeric character

We often use this regular expression when detecting user names and passwords .

The goal is ：

123
abc
123abc
acRa32EEE
bytefish
Jack2022

Regular expressions ：

/^[a-zA-Z0-9]+$/

• [a-zA-Z0–9] Match all letters and numbers

visualization ：

usage ：

04、allow space

If you want to leave spaces in the string , You can write regular expressions like this ：

/^[a-zA-Z0-9\s]+$/

• \s Match blanks .

usage ：

05、 E-mail

Email addresses can have many formats , It's hard to write regular expressions that match email addresses perfectly .

If we add some constraints , Then we have the following writing .

Regular expressions 1

^\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$

This is a RegularExpressionValidator stay ASP.NET One used in .

usage ：

Regular expressions 2

^\[email protected][a-zA-Z_]+?\.[a-zA-Z]{2,3}$

Simple email expression . Numbers are not allowed in domain names , And it is not allowed to use less than 2 One or more 3 A top-level field of letters （ Before they allow more ）.

usage ：

06、 password

Like email , Passwords may have different rules . Here are some common rules and related regular expressions .

The rules 1

^[a-zA-Z]\w{8,20}$

In this regular expression , The first character of the password must be a letter , It must contain at least 8 Characters and no more than 20 Characters , And you can't use division letters 、 Characters other than numbers and underscores .

usage ：

The rules 2：

/^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[^\w\s]).{8,}$/

• At least 8 Characters

• At least 1 Number characters

• At least 1 Lowercase letters

• At least 1 Capital letters

• At least 1 Special characters

07、 user name

May contain _ and — Alphanumeric string , The length is 3 To 16 Characters .

Example ：

bytefish
jon-snow
Rob_Stark

Regular expressions ：

/^[a-zA-Z0-9_-]{3,16}$/

usage ：

08、 website

Check whether the string is URL

/https?:\/\/(www\.)?[[email protected]:%._\+~#=]{2,256}\.[a-z]{2,6}\b([[email protected]:%_\+.~#()?&//=]*)/

usage ：

09、IP Address

IPv4

^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$

IPv6

(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))

10、 date

Date format using delimiters YYYY-MM-dd -

/([12]\d{3}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01]))/

usage ：

Date format dd-MM-YYYY Use separator - or . /

/^(?:(?:31(\/|-|\.)(?:0?[13578]|1[02]))\1|(?:(?:29|30)(\/|-|\.)(?:0?[1,3-9]|1[0-2])\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})$|^(?:29(\/|-|\.)0?2\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))$|^(?:0?[1-9]|1\d|2[0-8])(\/|-|\.)(?:(?:0?[1-9])|(?:1[0-2]))\4(?:(?:1[6-9]|[2-9]\d)?\d{2})$/

11、HTML label

take HTML Tags match attributes ：

/<\/?[\w\s]*>|<.+[\W]>/

usage ：

12、 Phone number

U.S. phone number format

The goal is ：

123-456-7890
[phone]
123 456 7890
123.456.7890
[phone]

Regular expressions ：

^(\+\d{1,2}\s)?\(?\d{3}\)?[\s.-]\d{3}[\s.-]\d{4}$

usage ：

summary

The above is what I share with you today 12 A common regular expression , I hope these regular expressions are useful to you .

Last , Thanks for reading .

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