JS regular expression system explanation (comprehensive summary)

1. Declaration and use

• Define... Through the constructor （ Generally not ）

let  Variable name = new RegExp(/ expression /);

• Literal direct definition （ Usually ）

let  Variable name = / expression /;

• Common methods （ It is generally used to detect whether the incoming string conforms to the rule and return a Boolean value ）

exp.test(" String to detect ")

2. Predefined classes and escape characters

• . [^\n\r] Any character other than line feed and carriage return
• \d [0-9] Numeric character digit
• \D [^0-9] Nonnumeric character
• \w [a-zA-Z0-9_] Word characters ( All English alphanumeric and _) word
• \W [^a-zA-Z0-9_] Nonword character
• \s [\f\r\n\t\v] Invisible characters space
• \S [^\f\r\n\t\v] Visible characters
• \f Indicates page change form feed
• \t Represents a horizontal tab table
• \v Represents a vertical tab vertical table
  
• \r,\n,\r\n The difference between ( By the way )
  In the evil old society , Typewriter line breaks （\n newline） Then it will only move down one line , You need to go back to the beginning of a line （\r return） To continue typing
  The old operating system also inherited this feature of the typewriter , However, users usually return to the beginning after line breaking , Therefore, the new operating system makes it easy to Enter The meaning of the key is changed to \r\n Or directly \n The meaning of is changed to “ Move to the beginning of the next line ”.
• | Represents or Or has the lowest priority Can pass () Raise priority

3. Character class

• Simple class [abc] Indicates the characters that can appear at this position
• Negative class [^abc] A character indicating that the position cannot appear
• Scope class [a-e] Indicates the range of characters that can appear at this position
• Combination class [a-xA-E0-9] Combination of range classes

4. The border , quantifiers , Brackets

• ^ Will match the starting position of the line or string
• ^ Only in [] Neicai means non On the outside, it means start
• $ Will match the end of the line or string
• ^$ together It must be this （ Exactly match ）
• “*” Repeat zero or more x>=0
• “+” Repeat one or more times x>=1
• “?” Repeat zero or one time x=(0||1)
• {n} n Time x=n
• {n,} repeat n Or more times x>=n
• {n,m} The number of repetitions is more than n Duodanbi m Less n<=x<=m
• () Means a group
• [] Represents the position of a character
• {} Number of times

5. Matching commonly used in projects (CV Necessary for Engineers )

// 1.  Match domestic phone number 
let tel = /^0\d{2,3}-\d{7,8}$/

// 2.  Match name 
let name = /^[\u4e00-\u9fa5]{2,}$/

// 3. Matching Tencent QQ Number 
let qq = /^[1-9]\d{4,10}$/

// 4.  Match cell phone number 
let phone = /^(13[0-9]|14[57]|15[0-9]|18[0-9])\d{8}$/

// 5. Match mailbox 
let emai = /^\w+([+-.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$/

// 6.  Verify Chinese 
let regex = /^[\u0391-\uFFE5]+$/;

// 7.  Verify ID card 
let idCrad = /^\d{6}(18|19|20)?\d{2}(0[1-9]|1[12])(0[1-9]|[12]\d|3[01])\d{3}(\d|X)$/;

// 8.  Validation of an integer 
let number = /^[-+]?\d*$/;

// 9.  Verify that the date format is YYYY-MM-DD hh:mm:ss Format 
let date = /^(\d{1,4})(-|\/)(\d{1,2})\2(\d{1,2}) (\d{1,2}):(\d{1,2}):(\d{1,2})$/;

// 10.  Verify that the characters entered are English letters 
let en = /^[a-zA-Z]+$/

// 11.  Baidu network disk link matching 
//  Support two link formats shared by Baidu 
//  Format 1 ： link : https://pan.baidu.com/s/15gzY8h3SEzVCfGV1xfkJ  Extraction code : vsuw  Copy this content after opening baidu network disk mobile phone App, It is more convenient to operate 
//  Format two ：http://pan.baidu.com/share/link?shareid=179436&uk=32720556  Extraction code : vsuw  Copy this content after opening baidu network disk mobile phone App, It is more convenient to operate 

let reg = /([http|https]*?:\/\/pan\.baidu\.com\/[(?:s\/){0,1}|(share)]*(?:[0-9a-zA-Z?=&])+)(?:.+:(?:\s)*)?([a-zA-Z]{4})?/;

// 12.  Whether or not there are decimals 
let  objRegExp= /^\d+\.\d+$/;

// 13.  Check if it's all from 8 Digit composition 
let reg = /^[0-9]{8}$/

1. I hope this article can help you , If there is a mistake , Please point out

2. Originality is not easy. , Please also use your little hands to make a fortune to support a wave （ Focus on 、 Comment on 、 give the thumbs-up 、 Collection ）
3. Thank you ！ We will continue to offer high-quality articles in the future
4. If in doubt , You can write to me ( The home page has Q)