Basic js Regular Expressions

1. "." is a wildcard that represents any character. For example, "a. c" can match "anc", "abc", and "acc ";

2. "[]", you can specify the matching characters in []. For example, "a [nbc] c" can match "anc", "abc", and "acc"

But it cannot match "ancc". a to z can be written as [a-z], 0 to 9 can be written as [0-9];

3. quantity limit symbol, indicating the number of matching times (or length:

Including: "*" -- 0 or multiple times

"+" -- Once or multiple times

"?" -- 0 or 1 time

"{N}" -- match n times, n is an integer

"{N, m}" -- number of times a number is matched from n to m; n and m are integers;

"{N ,}" -- match any number of times between n and infinity;

"{, M}" -- match any number of times between 0 and m;

They are placed behind the matching format:

For example:

Phone number: 024-84820482,02484820482 (assume that the first 3 or 4 digits are followed by 7 or 8 digits, and the minus sign in the middle is optional)

All are compliant, so you can use the following format to match: [0-9] {3, 4 }-? [0-9] {7,8 };

Note: "" is an escape character, because "-" represents a range in a regular expression, for example, [0-9],

Therefore, the escape character "" is required for conversion;

4. "^" indicates no symbols that do not match. For example, [^ z] [a-z] + can match all characters starting with "z ".

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

If ^ is placed outside [], it indicates a string starting with []. ^ [az] [a-z] + indicates an English character whose length starts with a or z is greater than or equal to 2.

String;

5. "|" or operator. For example, a [n | bc | cb] c can match "abcc", "anc", and "acbc ";

6. "$" ends with the character above it. For example, AB + $ can be matched by "abb" and "AB;

7. Some Simple Representation Methods:

D Represents [0-9]; D represents [^ 0-9]; w represents [A-Z0-9]; W represents [^ A-Z0-9]; s represents [tnrf], that is, the space character includes tab

, Space, etc.; S indicates [^ tnrf], which is a non-space character;

8. Common matching:

Match Chinese characters: "[u4e00-u9fa5]";

Match double byte characters (including Chinese characters): "[^ x00-xff]";

Match the Regular Expression of null rows: "n [s |] * r ";

Match the regular expression marked in HTML: "/. * | /";

Regular Expression matching the first and last spaces: "(^ s *) | (s * $ )";

Match a non-negative integer (positive integer + 0): "^ d + $ ";

Match a positive integer: "^ [0-9] * [1-9] [0-9] * $ ";

Match a non-positive integer (negative integer + 0): "^ (-d +) | (0 +) $ ";

Match a negative integer: "^-[0-9] * [1-9] [0-9] * $ ";

Matched INTEGER: "^ -? D + $ ";

Match non-negative floating point number (Positive floating point number + 0): "^ d + (. d + )? $"

Match 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 + )?)) $ // Match a non-Positive floating point number (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

Match floating point: "^ (-? D +) (. d + )? $ ";

Match a string consisting of digits, 26 English letters, or underscores: "^ w + $ ";

Matching email address: "^ [w-] + (. [w-] +) * @ [w-] + (. [w-] +) + $ ";

Match url: "^ [a-zA-z] +: // match (w + (-w + )*)(. (w + (-w + )*))*(? S *)? $"

1. "." is a wildcard that represents any character. For example, "a. c" can match "anc", "abc", and "acc ";
2. "[]", you can specify the matching characters in []. For example, "a [nbc] c" can match "anc", "abc", and "acc"
But it cannot match "ancc". a to z can be written as [a-z], 0 to 9 can be written as [0-9];