The basic knowledge of JS regular expression

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: 024-84820482,02484820482 (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 beginning of "Z" all words

String (length greater than 2, because "+" means the number of times greater than or equal to 1, starting from the second is lowercase English characters);

If ^ is placed outside [] a string that begins with []; ^[az][a-z]+ represents an English character with a length greater than or equal to 2 at the beginning of a or Z

String

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 indicates [^a-z0-9];s [TNRF], which is the space character including tab

, spaces 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 ";

A regular expression that matches an HTML tag: "/.*|/";

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 numbers

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*)? $ "

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];