Usage of JavaScript Regular expressions

1, "." is a wildcard that represents any one character, for example: "A.C" can match "ANC", "ABC", "ACC";

2, "[]", in [] can specify the required matching characters, such as: "A[nbc]c" can match "ANC", "ABC", "ACC", but can not match "ANCC", A to Z can be written [a-z],0 to 9 can be written [0-9];

3, Quantity qualifying symbol, indicating the number of matches (or length) of the symbol:
Includes: "*"--0 or more times
"+"--1 or more times
“?” --0 or 1 times
' {n} '--match n times, N is an integer
' {n,m} '--the number of occurrences of a number from N to M; n and m are integers;
"{N,}"--matches any number of times between N and Infinity;
"{, M}"--matches any number of times between 0 and M;
They are placed behind the matching format:
For example:
Phone Number: 0755-12345678,075512345678 (assuming the front 3 or 4 digits, the back 7 or 8 digits, and the middle minus is optional)
are compliant, they can be matched in the following format: [0-9]{3,4}-? [0-9] {7,8};
Note: "" is an escape character because "-" is used in a regular expression to represent a range of meanings, for example: [0-9] as described above,
So it needs the escape character "" to be escaped to use;

4, "^" is no symbol, indicating do not want to match the symbol, for example: [^z][a-z]+ can match all except the "Z" of all the strings (length greater than 2, because "+" is greater than or equal to 1 of the number of times, starting from the second is lowercase English characters);
If ^ is placed outside [], it represents a string beginning with []; ^[az][a-z]+ represents an English string with a length greater than or equal to 2 at the beginning of A or Z;

5, "|" Or operators, such as: A[n|bc|cb]c can Match "ABCC", "ANC", "ACBC";
6, "$" at the end of the character before it; for example: ab+$ can be "ABB", "AB" match;

7. Some simple ways to express:
D means [0-9];D Express [^0-9];W [a-z0-9]; W said [^a-z0-9];s [TNRF], is the space character including tab, space and so on; s represents [^TNRF], is not a space character;

8. Common matching:
Match Chinese characters: "[U4e00-u9fa5]";
Match Double-byte characters (including Chinese characters): "[^x00-xff]";
A regular expression that matches a blank row: "n[s|] *r ";
Regular expression matching HTML tags: "/< (. *) >.*</1>|< (. *)/>/";
Matching a regular expression with a trailing space: "(^s*) | (s*$) ";
Match nonnegative integer (positive integer + 0): "^d+$";
Match positive integer: "^[0-9]*[1-9][0-9]*$";
Match a non positive integer (negative integer + 0): "^ ((-d+) | ( 0+)) $ ";
Match negative integer: "^-[0-9]*[1-9][0-9]*$";
Match integer: "^-?d+$";
matching nonnegative floating-point numbers (positive floating-point number + 0): "^d+ (. d+)? $"
Matching 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]*)] $ ";
^ ((-d+ (. d+)?) | (0+ (. 0+)?)) $//matching non-positive floating-point numbers (negative floating-point number + 0)
^ (-([0-9]+. [0-9]*[1-9][0-9]*) | ([0-9]*[1-9][0-9]*. [0-9]+) | ([0-9]*[1-9][0-9]*))] $///Match negative floating-point number
Matching floating-point number: "^ (-?d+) (. d+)? $";
Match a string of numbers, 26 English letters, or underscores: "^w+$";
Match email address: "^[w-]+. [ w-]+) *@[w-]+ (. [ w-]+) +$ ";
Match URL: "^[a-za-z]+://match (w+ (-w+) *) (. w+ (-w+) *) *) * (? s*)? $ "

Some common regular expressions

<strong>//Matching Email address </strong>
w+ ([-+. '] w+) *@w+ ([-.] w+) *.w+ ([-.] w+) *
Match Chinese characters
[U4e00-u9fa5]
<strong>//match 15-bit or 18-bit ID </strong>
(^d{15}$/) | (D{17} (?:d |x| X) $
<strong>//Matching IP address </strong>
D+.d+.d+.d+
Match Blank Line
Ns*r//Can be used to delete blank lines
Match Double-byte characters (including Chinese characters)
[^x00-xff]
Match the trailing whitespace characters
^s*|s*$
<strong>//matching domestic phone number </strong>
D{3}-D{8}|D{4}-D{7}///commentary: match form such as 0511-4405222 or 021-87888822
<strong>//Matching mobile number </strong>
/^1 (3|5|8) d{9}$/
Match img Tags
&AMP;LT;IMG[^&AMP;GT;] +&gt;
Match img Address
&lt;img.+?src= ([' "]?) ([^&gt;s]+) 1.*?&gt;
Matching HTML tags
&lt; (s*?) [^&gt;] *&gt;. *?&lt;/1&gt;|&lt;. *? /&gt;
<strong>//Matching URL URLs </strong>
(FTP|HTTP|HTTPS)://(w+:{0,1}w*@)? (s+) (: [0-9]+)? (/|/([w#!:.? +=&amp;%@!-/])?
<strong>//matching Tencent QQ number:</strong>
[1-9] [0-9] {4,}//Commentary: Tencent QQ number starting from 10000
Match China ZIP code
[1-9]d{5} (?! D//Commentary: China postal code is 6 digits
Match a specific number:
^d+$//matching numbers
^[1-9]d*$//Matching positive integer
^-[1-9]d*$//matching negative integers
^-? [1-9]d*$//matching integer
^[1-9]d*|0$//matching nonnegative integer (positive integer + 0)
^-[1-9]d*|0$//matching non positive integer (negative integer + 0)
^[1-9]d*.d*|0.d*[1-9]d*$//matching positive floating-point numbers
^-([1-9]d*.d*|0.d*[1-9]d*) $//matching negative floating-point number
^-? ([1-9]d*.d*|0.d*[1-9]d*|0?. 0+|0) $//matching floating-point number
^[1-9]d*.d*|0.d*[1-9]d*|0? 0+|0$//matching nonnegative floating-point number (positive floating-point number + 0)
^ (-([1-9]d*.d*|0.d*[1-9]d*)) |? 0+|0$//matching non-positive floating-point numbers (negative floating-point number + 0)
Match a specific string:
^[a-za-z]+$//Match a string of 26 English letters
^[a-z]+$//Match a string of 26 uppercase letters
^[a-z]+$//Match string consisting of 26 lowercase letters
^[a-za-z0-9]+$//Match a string of numbers and 26 English letters
^w+$//Match A string of numbers, 26 English letters, or underscores
^[a-za-z]w{5,17}$//starts with a letter, length between 6~18, can only contain characters, numbers, and underscores