Summary of JS Regular expressions

New Regular expression

var reg =/Regular expression/(g,i,m)

var reg = REGEXP (' Mutations ', (G,I,M))

The G Global match does not represent a match only to the first

I ignore case

M multi-line matching

1. Verification

When used for validation, it is often necessary to add ^ and $ respectively to match the entire string to be validated;

2. Search and replace

To add \b to the front and back

Character class matching

[...] Find any character between square brackets
[^ ...] Find any characters that are not in square brackets
[A-z] find any characters from small to lowercase Z
[A-z] find any characters from uppercase A to uppercase Z
[A-z] find any characters from uppercase A to lowercase Z
. Find a single character, except line breaks and line terminators
\w find word characters, equivalent to [a-za-z0-9]
\w Find non-word characters, equivalent to [^a-za-z0-9]
\s finding whitespace characters
\s finding non-whitespace characters
\d find number, equivalent to [0-9]
\d Find non-numeric characters, equivalent to [^0-9]
\b Match word boundaries
\ r Find Carriage return character
\ t find a tab
To find a NULL character
\ nto find line breaks

repeating character matching

{N,m} matches the previous item at least n times, but cannot exceed m times
{N,} matches the previous item n or more times
{n} matches the previous item n times
N? Matches the previous item 0 or 1 times, which means the previous item is optional, equivalent to {0,1}
n+ matches the previous item 1 or more times, equivalent to {1,}
n matches the previous item 0 or more times, equivalent to {0,}
n$ matches any string ending with n
^n matches any string starting with N
=n matches any string immediately followed by the specified string n
?! n matches any string that is not followed by the specified string n

' abc123 '. Replace (/\w (? =\d)/, ' 123 ')"ab123123"

' abc123 '. Replace (/\w (?! \d)/, ' 123 ') "123bc123"

　　

Match a specific number

^[1-9]\d*$ matching positive integers
^-[1-9]\d*$ matching negative integers
^-? [0-9]\d*$ Match integer
^[1-9]\d*|0$ matches non-negative integers (positive integers + 0)
^-[1-9]\d*|0$ matches a non-positive integer (negative integer + 0)
^[1-9]\d*\.\d*|0\.\d*[1-9]\d*$ matching a positive floating point number
^-([1-9]\d*\.\d*|0\.\d*[1-9]\d*) $ matches negative floating-point number
^-? ([1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0+|0) $ match floating point number
^[1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0+|0$ matched non-negative floating-point number (positive floating point + 0)
^ (-([1-9]\d*\.\d*|0\.\d*[1-9]\d*)) |0?\.0+|0$ matches non-positive floating-point number (negative floating-point number + 0)

Match a specific string

^[a-za-z]+$ matches a string consisting of 26 English letters
^[a-z]+$ matches a string of 26 English letters in uppercase
^[a-z]+$ matches a string of 26 English letters in lowercase
^[a-za-z0-9]+$ matches a string consisting of a number and 26 English letters
^\w+$ matches a string of numbers, 26 English letters, or underscores

Group () () () $1$2$3

Test Reg.test ()

var reg =/abc/g;    var str = "123ABC456ABC";    Console.log (Reg.lastindex);//0    Console.log (reg.test (str));//true    Console.log (reg.lastindex);//6    Console.log (Reg.test (str));//true    Console.log (reg.lastindex);//12    Console.log (reg.test (str));//false

Reg.exec ()

var str = "xyz";  var reg1 =/x/;  var reg2 =/a/;  var res1 = reg1.exec (str);  var res2 = reg2.exec (str);  Console.log (res1);//["X", index:0, Input: "xyz"]  Console.log (res2);//null

Reg.search ()

var str = "ABCDCEF";  Console.log (Str.search (/c/g));//2

　　

Summary of JS Regular expressions