1. Regular expressions are often used in websites. Here are some explanations and examples for your reference and modification:
2. "^ d+$"//Non negative integer (positive integer+0)
3. "^ [0-9] * [1-9] [0-9] * $"//Positive integer
4. "^ ((- d+) | (0+)) $"//Non positive integer (negative integer+0)
5. "^ - [0-9] * [1-9] [0-9] * $"//Negative integer
6. "^ -? D+$"//Integer
7. "^ d+(. d+)? $"//Non negative floating point number (positive floating point number+0)
8. "^ (([0-9]+. [0-9] * [1-9] [0-9] *) | ([0-9] * [1-9] [0-9] *. [0-9]+) | ([0-9] * [1-9] [0-9] *)) $"//Positive floating point number
9. "^ ((- d+(. d+)?) | (0+(. 0+)?)) $"//Non positive floating point number (negative floating point number+0)
10. "^ (- (([0-9]+. [0-9] * [1-9] [0-9] *) | ([0-9] * [1-9] [0-9] *. [0-9]+) | ([0-9] * [1-9] [0-9] *)) $"//Negative floating point number
11. "^ (-? D+) (. d+)? $"//floating point number
12. "^ [A-Za-z]+$"//A string consisting of 26 English letters
13. "^ [A-Z]+$"//A string composed of 26 uppercase English letters
14. "^ [a-z]+$"//A string composed of 26 lowercase English letters
15. "^ [A-Za-z0-9]+$"//A string consisting of numbers and 26 English letters
16. "^ w+$"//A string consisting of numbers, 26 English letters or underscores
17. "^ [w -]+(. [w -]+) * @ [w -]+(. [w -]+)+$"//email address
18.    "^[a-zA-z]+://(w+(-w+)*)(.(w+(-w+)*))*(?S*)?$"　　//url
19./^ (d {2} | d {4}) - ((0 ([1-9] {1})) | (1 [1 | 2])) - ([0-2] ([1-9] {1})) | (3 [0 | 1]) $//Year Month Day
20./^ ((0 ([1-9] {1})) | (1 [1 | 2]))/([0-2] ([1-9] {1})) | (3 [0 | 1])/(d {2} | d {4}) $//Month/Day/Year
21.    "^([w-.]+)@(([[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.)|(([w-]+.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(]?)$"   //Emil
22.    /^((+?[0-9] {2,4}- [0-9] {3,4}- )|([0-9] {3,4}- ))? ([0-9]{7,8})(-[0-9]+)?$/ //Phone number
23. "^ (d {1,2} | 1dd | 2 [0-4] d | 25 [0-5]). (d {1,2} | 1dd | 2 [0-4] d | 25 [0-5]). (d {1,2} | 1dd | 2 [0-4] d | 25 [0-5]). (d {1,2} | 1dd | 2 [0-4] d | 25 [0-5]) $"//IP address
24.    
25. Regular expression matching Chinese characters: [u4e00-u9fa5]
26. Matching double byte characters (including Chinese characters): [^ x00 xff]
27. Regular expression matching empty lines: n [s |] * r
28. Regular expressions matching HTML tags:/<(. *)>. *</1>|<(. *)/>/
29. Regular expressions matching first and last spaces: (^ s *) | (s * $)
30. Regular expression matching email address: w+([-+.] w+) * @ w+([-.] w+) *. w+([-.] w+)*
31. Regular expression matching URL: ^ [a-zA-z]+://( w+(- w+) *) (. ( w+(- w+) *) * (? S *)$
32. Whether the matching account number is legal (letters start, 5-16 bytes are allowed, alphanumeric underscores are allowed): ^ [a-zA-Z] [a-zA-Z0-9_] {4,15}$
33. Matching domestic telephone number: (d {3}- |d {4}- )? (d{8}|d{7})?
34. Match Tencent QQ number: ^ [1-9] * [1-9] [0-9]*$
35.    
36.    
37. Metacharacters and their behavior in the context of regular expressions:
38.    
39. Mark the next character as a special character, or a literal character, or a backward reference, or an octal escape character.
40.    
41. ^ matches the start of the input string. If the Multiline property of the RegExp object is set, ^ also matches the position after 'n' or 'r'.
42.    
43. $matches the end of the input string. If the Multiline attribute of the RegExp object is set, $also matches the position before 'n' or 'r'.
44.    
45. * Matches the preceding subexpression zero or more times.
46.    
47.+matches the preceding subexpression one or more times+ Equivalent to {1,}.
48.    
49.    ? Matches the previous subexpression zero or once.? Equivalent to {0,1}.
50.    
51. {n} n is a non negative integer, matching the determined n times.
52.    
53. {n,} n is a non negative integer, matching at least n times.
54.    
55. {n, m} m and n are non negative integers, where n<=m. The minimum number of matches is n and the maximum number of matches is m. There can be no space between a comma and two numbers.
56.    
57.    ? When this character is immediately followed by any other qualifier (*,+,?, {n}, {n,}, {n, m}), the matching pattern is non greedy. The non greedy pattern matches as few strings as possible, while the default greedy pattern matches as many strings as possible.
58.    
59.    . Matches any single character except "n". To match any character including 'n', use a pattern like '[. n]'.
60. (pattern) Match pattern and obtain this match.
61.    
62. (?: pattern) Matches the pattern but does not obtain the matching result, that is, it is a non acquisition match and will not be stored for future use.
63.    
64. (?=pattern) Forward pre query, which matches the search string at the beginning of any string matching pattern. This is a non acquisition match, that is, the match does not need to be acquired for future use.
65.    
66. (?! pattern) negative preview, which is opposite to (?=pattern)
67.    
68. x | y matches x or y.
69.    
70. [xyz] character set.
71.    
72. [^ xyz] Negative character set.
73.    
74. [a-z] Character range, matching any character within the specified range.
75.    
76. [^ a-z] Negative character range, matching any character not within the specified range.
77.    
78. b Match a word boundary, that is, the position between the word and the space.
79.    
80. B Matches non word boundaries.
81.    
82. cx matches the control character indicated by x.
83.    
84. d Matches a numeric character. Equivalent to [0-9].
85.    
86. D matches a non numeric character. Equivalent to [^ 0-9].
87.    
88. f Matches a new page character. Equivalent to x0c and cL.
89.    
90. n matches a newline character. Equivalent to x0a and cJ.
91.    
92. r matches a carriage return. Equivalent to x0d and cM.
93.    
94. s Matches any white space characters, including spaces, tabs, page feeds, and so on. Equivalent to [fnrtv].
95.    
96. S matches any non whitespace character. Equivalent to [^ fnrtv].
97.    
98. t Matches a tab. Equivalent to x09 and cI.
99.    
100. v matches a vertical tab. Equivalent to x0b and cK.
101.    
102. w Matches any word character including underscores. Equivalent to '[A-Za-z0-9_]'.
103.    
104. W Matches any non word character. Equivalent to '[^ A-Za-z0-9_]'.
105.    
106. xn matches n, where n is the hexadecimal escape value. The hexadecimal escape value must be two digits long.
107.    
108. num matches num, where num is a positive integer. Reference to the matched obtained.
109.    
110. n identifies an octal escape value or a backward reference. If n is preceded by at least n obtained sub expressions, n is a backward reference. Otherwise, if n is an octal digit (0-7), then n is an octal escape value.
111.    
112. nm identifies an octal escape value or a backward reference. If there are at least sub expressions obtained before nm, nm is a backward reference. If there are at least n acquisitions before nm, then n is a backward reference followed by the text m. If the previous conditions are not met, if n and m are octal digits (0-7), nm will match the octal escape value nm.
113.    
114. nml If n is an octal digit (0-3), and m and l are both octal digits (0-7), the octal escape value nml is matched.
115.    
116. un matches n, where n is a Unicode character represented by four hexadecimal digits.
117.    
118. Regular expressions matching Chinese characters: [u4e00-u9fa5]
119.    
120. Matching double byte characters (including Chinese characters): [^ x00 xff]
121.    
122. Regular expression matching empty lines: n [s |] * r
123.    
124. Regular expressions matching HTML tags:/<(. *)>. *</1>|<(. *)/>/
125.    
126. Regular expressions matching first and last spaces: (^ s *) | (s * $)
127.    
128. Regular expression matching email address: w+([-+.] w+) * @ w+([-.] w+) *. w+([-.] w+)*
129.    
130. Regular expressions matching URL: //([w -]+.)+[w -]+(/[w -./?%&=] *)?
131.    
132. Use regular expressions to limit the input content of the text box in the web form:
133.    
134. Use regular expressions to restrict input to Chinese only: onkeyup="value=value. replace (/[^ u4E00-u9FA5]/g, '')" onforecast="clipboardData. setData ('text ', clipboardData. getData ('text'). replace (/[^ u4E00-u9FA5]/g, '')"
135.    
136. Use regular expressions to restrict the input of only full width characters: onkeyup="value=value. replace (/[^ uFF00 uFFFF]/g, '')" onforecast="clipboardData. setData ('text ', clipboardData. getData ('text'). replace (/[^ uFF00 uFFFF]/g, '')"
137.    
138. Use regular expressions to limit the number you can only enter: onkeyup="value=value. replace (/[^ d]/g, '')" onforecast="clipboardData. setData ('text ', clipboardData. getData ('text'). replace (/[^ d]/g, '')"
139.    
140. Use regular expressions to restrict the input of numbers and English only: onkeyup="value=value. replace (/[W]/g, '')" onbeforecast="clipboardData. setData ('text ', clipboardData. getData ('text'). replace (/[^ d]/g, '')"
141.    
142.==========Common Regular Formula
143.    
144.    
145.    
146. Regular expressions matching Chinese characters: [u4e00-u9fa5]
147.    
148. Matching double byte characters (including Chinese characters): [^ x00 xff]
149.    
150. Regular expression matching empty lines: n [s |] * r
151.    
152. Regular expressions matching HTML tags:/<(. *)>. *</1>|<(. *)/>/
153.    
154. Regular expressions matching first and last spaces: (^ s *) | (s * $)
155.    
156. Regular expression matching IP address:/(d+) (d+). (d+). (d+)/g //
157.    
158. Regular expression matching email address: w+([-+.] w+) * @ w+([-.] w+) *. w+([-.] w+)*
159.    
160. Regular expressions matching URL: //(/[w -]+.)+[w -]+(/[w -./?%&=] *)?
161.    
162. SQL statement: ^ (select | drop | delete | create | update | insert)*$
163.    
164. 1. Non negative integer: ^ d+$
165.    
166. 2. Positive integer: ^ [0-9] * [1-9] [0-9]*$
167.    
168. 3. Non positive integer: ^ ((- d+) | (0+))$
169.    
170. 4. Negative integer: ^ - [0-9] * [1-9] [0-9]*$
171.    
172. 5. Integer: ^ -? d+$
173.    
174. 6. Non negative floating point number: ^ d+(. d+)$
175.    
176. 7. Positive floating point number: ^ ((0-9)+ [0-9]*[1-9][0-9]*)|([0-9]*[1-9][0-9]*.[0-9]+)|([0-9]*[1-9][0-9]*))$
177.    
178. 8. Non positive floating point number: ^ ((- d+. d+)?)| (0+(.0+)?))$
179.    
180. 9. Negative floating point number: ^ (- (positive floating point number regular expression))$
181.    
182. 10. English string: ^ [A-Za-z]+$
183.    
184. 11. English capital string: ^ [A-Z]+$
185.    
186. 12. English lowercase string: ^ [a-z]+$
187.    
188. 13. English character number string: ^ [A-Za-z0-9]+$
189.    
190. 14. English number plus underscore string: ^ w+$
191.    
192. 15. E-mail address: ^ [w -]+(. [w -]+) * @ [w -]+(. [w -]+)+$
193.    
194.    16、URL：^[a-zA-Z]+://(w+(-w+)*)(.(w+(-w+)*))*(?s*)?$
195. Or: ^ //[A-Za-z0-9]+ [A-Za-z0-9]+[/=?%-&_~`@[]':+!]* ([^<>""])*$
196.    
197. 17. Postal code: ^ [1-9] d {5}$
198.    
199. 18. Chinese: ^ [u0391-uFFE5]+$
200.    
201. 19. Telephone No.: ^ (((d {2,3})) | (d {3}- ))? ((0d{2,3})|0d {2,3}- )? [1-9]d{6,7}(-d{1,4})?$
202.    
203. 20. Mobile phone number: ^ (((d {2,3})) | (d {3}- ))? 13d{9}$
204.    
205. 21. Double byte characters (including Chinese characters): ^ x00 xff
206.    
207. 22. Matching first and last spaces: (^ s *) | (s * $) (trim functions like vbscript)
208.    
209. 23. Matching HTML tags:<(. *)>. *</1>|<(. *)/>
210.    
211. 24. Matching blank lines: n [s |] * r
212.    
213. 25. Extract the network link in the information: (h | H) (r | R) (e | E) (f | F) *=* ('| ")? (w | |/|.)+(' |" | * |>)?
214.    
215. 26. Email address in extracted information: w+([-+.] w+) * @ w+([-.] w+) *. w+([-.] w+)*
216.    
217.27. Extract the picture link in the information: (s | S) (r | R) (c | C) *=* ('| ")? (w | |/|.)+(' |" | * |>)?
218.    
219.28. IP address in extracted information: (d+) (d+). (d+). (d+)
220.    
221. 29. Chinese mobile phone number in the extracted information: (86) * 0 * 13d {9}
222.    
223.30. Retrieve the Chinese fixed telephone number in the information: ((d {3,4}) | d {3,4}- |s)? d{8}
224.    
225. 31. Retrieve the Chinese telephone number (including mobile and fixed telephones) in the information: ((d {3,4}) | d {3,4}- |s)? d{7,14}
226.    
227.32. Postal code of China in the extracted information: [1-9] {1} (d+) {5}
228.    
229.33. Floating point number (i.e. decimal) in extracted information: (-? D *)? d+
230.    
231. 34. Extract any number in the information: (-? D *) (. d+)?
232.    
233.    35、IP：(d+). (d+). (d+). (d+)
234.    
235. 36. Telephone area code:/^ 0d {2,3}$/
236.    
237.37 Tencent QQ No.: ^ [1-9] * [1-9] [0-9]*$
238.    
239. 38. Account number (beginning with a letter, 5-16 bytes are allowed, alphanumeric underscores are allowed): ^ [a-zA-Z] [a-zA-Z0-9_] {4,15}$
240.    
241. 39. Chinese, English, numbers and underscores: ^ [u4e00-u9fa5_a-zA-Z0-9]+$

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