1. Regular expressions are often used when building websites. Here are some explanations and examples for your reference and modification only:
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 consisting of 26 uppercase English letters
14. "^[a-z]+$" //A string consisting of 26 lowercase English letters
15. "^[A-Za-z0-9]+$" // 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 to match Chinese characters: [u4e00-u9fa5]
26. Match double-byte characters (including Chinese characters): [^x00-xff]
27. Regular expression to match blank lines: n[s| ]*r
28. Regular expression to match HTML tags: /<(.*)>.*|<(.*) />/
29. Regular expression matching leading and trailing spaces: (^s*)|(s*$)
30. Regular expression to match email address: w+([-+.]w+)*@w+([-.]w+)*.w+([-.]w+)*
31. Regular expression to match URL: ^[a-zA-z]+://(\w+(-\w+)*)(\.(\w+(-\w+)*))*(\? \S*)?$
32. Whether the matching account is legal (starting with a letter, 5-16 bytes allowed, alphanumeric underscores allowed): ^[a-zA-Z][a-zA-Z0-9_]{4,15}$
33. Match domestic phone numbers: (d{3}-|d{4}-)?(d{8}|d{7})?
34. Matching 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, a literal character, a backreference, or an octal escape character.
40.
41. ^ matches the beginning 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 position of the input string. If the Multiline property of the RegExp object is set, $ also matches the position before 'n' or 'r'.
44.
45. * Matches the previous subexpression zero or more times.
46.
47. + Matches the previous subexpression one or more times. + is equivalent to {1,}.
48.
49. ? Match the previous subexpression zero or one time. ? Equivalent to {0,1}.
50.
51. {n} n is a non-negative integer that matches a certain number of n times.
52.
53. {n,} n is a non-negative integer that matches at least n times.
54.
55. {n,m} m and n are both non-negative integers, where n <= m. Match at least n times and at most m times. There cannot be a space between the comma and the two numbers.
56.
57. ? When the character immediately follows any other limiter (*, +, ?, {n}, {n,}, {n,m}), the matching pattern is non-greedy. Non-greedy mode matches as little of the searched string as possible, while the default greedy mode matches as much of the searched string as possible.
58.
59. . Matches any single character except "n". To match any character including 'n', use a pattern like '[.n]'.
60. (pattern) matches pattern and gets this match.
61.
62. (?:pattern) matches pattern but does not obtain the matching result, which means that this is a non-acquisition match and is not stored for later use.
63.
64. (?=pattern) Forward lookup, matches the search string at the beginning of any string that matches pattern. This is a non-fetch match, that is, the match does not need to be fetched for later use.
65.
66. (?!pattern) negative preview, opposite to (?=pattern)
67.
68. x|y matches x or y.
69.
70. [xyz] character set.
71.
72. [^xyz] Negative value character set.
73.
74. [a-z] character range, matches any character within the specified range.
75.
76. [^a-z] Negative character range, matches any character that is not within the specified range.
77.
78. b matches a word boundary, which refers to the position between a word and a space.
79.
80. B matches non-word boundaries.
81.
82. cx matches the control character specified 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 form feed 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 character. Equivalent to x0d and cM.
93.
94. s matches any whitespace character, including spaces, tabs, form feeds, etc. Equivalent to [fnrtv].
95.
96. S matches any non-whitespace character. Equivalent to [^ fnrtv].
97.
98. t matches a tab character. Equivalent to x09 and cI.
99.
100. v matches a vertical tab character. Equivalent to x0b and cK.
101.
102. w matches any word character including an underscore. 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 exactly two digits long.
107.
108. num matches num, where num is a positive integer. A reference to the match obtained.
109.
110. n identifies an octal escape value or a backreference. n is a backreference if n is preceded by at least n fetched subexpressions. Otherwise, if n is an octal number (0-7), then n is an octal escape value.
111.
112. nm identifies an octal escape value or a backreference. If nm is preceded by at least nm fetched subexpressions, nm is a backreference. If nm is preceded by at least n gets, then n is a backreference followed by the literal m. If neither of the previous conditions is true, and if n and m are both 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), then matches the octal escape value nml.
115.
116. un matches n, where n is a Unicode character represented by four hexadecimal digits.
117.
118. Regular expression to match Chinese characters: [u4e00-u9fa5]
119.
120. Match double-byte characters (including Chinese characters): [^x00-xff]
121.
122. Regular expression to match blank lines: n[s| ]*r
123.
124. Regular expression to match HTML tags: /<(.*)>.*|<(.*) />/
125.
126. Regular expression matching leading and trailing spaces: (^s*)|(s*$)
127.
128. Regular expression to match email addresses: w+([-+.]w+)*@w+([-.]w+)*.w+([-.]w+)*
129.
130. Regular expression to match URL: http://([w-]+.)+[w-]+(/[w- ./?%&=]*)?
131.
132. Use regular expressions to limit the input content of text boxes in web forms:
133.
134. Use regular expressions to limit input to Chinese only: onkeyup="value=value.replace(/[^u4E00-u9FA5]/g,'')" onbeforepaste="clipboardData.setData('text',clipboardData.getData( 'text').replace(/[^u4E00-u9FA5]/g,''))"
135.
136. Use regular expressions to limit the input of only full-width characters: onkeyup="value=value.replace(/[^uFF00-uFFFF]/g,'')" onbeforepaste="clipboardData.setData('text',clipboardData.getData ('text').replace(/[^uFF00-uFFFF]/g,''))"
137.
138. Use regular expressions to limit input to numbers: onkeyup="value=value.replace(/[^d]/g,'') "onbeforepaste="clipboardData.setData('text',clipboardData.getData('text ').replace(/[^d]/g,''))"
139.
140. Use regular expressions to limit input to numbers and English only: onkeyup="value=value.replace(/[W]/g,'') "onbeforepaste="clipboardData.setData('text',clipboardData.getData(' text').replace(/[^d]/g,''))"
141.
142. =========Commonly used regular expressions
143.
144.
145.
146. Regular expression to match Chinese characters: [u4e00-u9fa5]
147.
148. Match double-byte characters (including Chinese characters): [^x00-xff]
149.
150. Regular expression to match blank lines: n[s| ]*r
151.
152. Regular expression to match HTML tags: /<(.*)>.*|<(.*) />/
153.
154. Regular expression matching leading and trailing spaces: (^s*)|(s*$)
155.
156. Regular expression to match IP address: /(d+).(d+).(d+).(d+)/g //
157.
158. Regular expression to match email address: w+([-+.]w+)*@w+([-.]w+)*.w+([-.]w+)*
159.
160. Regular expression to match URL: http://(/[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 integers: ^((-d+)|(0+))$
169.
170. 4. Negative integers: ^-[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 numbers: ^((-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 and number string: ^[A-Za-z0-9]+$
189.
190. 14. Alphanumeric plus underline 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: ^http://[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. Phone number: ^(((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. Match leading and trailing spaces: (^s*)|(s*$) (trim function like vbscript)
208.
209. 23. Match HTML tags: <(.*)>.*|<(.*) />
210.
211. 24. Match blank lines: n[s| ]*r
212.
213. 25. Extract network links in the information: (h|H)(r|R)(e|E)(f|F) *= *('|")?(w|\|/|.)+ ('|"| *|>)?
214.
215. 26. Extract the email address in the information: w+([-+.]w+)*@w+([-.]w+)*.w+([-.]w+)*
216.
217. 27. Extract the picture link in the information: (s|S)(r|R)(c|C) *= *('|")?(w|\|/|.)+('|"| *|>)?
218.
219. 28. Extract the IP address in the information: (d+).(d+).(d+).(d+)
220.
221. 29. Extract the Chinese mobile phone number in the information: (86)*0*13d{9}
222.
223. 30. Extract the Chinese fixed phone number in the information: ((d{3,4})|d{3,4}-|s)?d{8}
224.
225. 31. Extract Chinese phone numbers (including mobile and landline phones) from the information: ((d{3,4})|d{3,4}-|s)?d{7,14}
226.
227. 32. Extract the Chinese postal code in the information: [1-9]{1}(d+){5}
228.
229. 33. Extract floating point numbers (i.e. decimals) in the information: (-?d*).?d+
230.
231. 34. Extract any number in the information: (-?d*)(.d+)?
232.
233. 35. IP: (d+).(d+).(d+).(d+)
234.
235. 36. Telephone area code: /^0d{2,3}$/
236.
237. 37. Tencent QQ number: ^[1-9]*[1-9][0-9]*$
238.
239. 38. Account number (starting with a letter, allowing 5-16 bytes, allowing alphanumeric underscores): ^[a-zA-Z][a-zA-Z0-9_]{4,15}$
240.
241. 39. Chinese, English, numbers and underline: ^[u4e00-u9fa5_a-zA-Z0-9]+$
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
