js match regex

1//Declare Reg using slash
2let reg = /abc/
3//Declare using class, useful for buil a RegExp from a variable
4reg = new RegExp('abc')
5
6//Option you must know: i -> Not case sensitive, g -> match all the string
7let str = 'Abc abc abc'
8str.match(/abc/) //Array(1) ["abc"] match only the first and return
9str.match(/abc/g) //Array(2) ["abc","abc"] match all
10str.match(/abc/i) //Array(1) ["Abc"] not case sensitive
11str.match(/abc/ig) //Array(3) ["Abc","abc","abc"]
12//the equivalent with new RegExp is
13str.match('abc', 'ig') //Array(3) ["Abc","abc","abc"]

1// Javascript Regex Reference
2//  /abc/	A sequence of characters
3//  /[abc]/	Any character from a set of characters
4//  /[^abc]/	Any character not in a set of characters
5//  /[0-9]/	Any character in a range of characters
6//  /x+/	One or more occurrences of the pattern x
7//  /x+?/	One or more occurrences, nongreedy
8//  /x*/	Zero or more occurrences
9//  /x?/	Zero or one occurrence
10//  /x{2,4}/	Two to four occurrences
11//  /(abc)/	A group
12//  /a|b|c/	Any one of several patterns
13//  /\d/	Any digit character
14// /\w/	An alphanumeric character (“word character”)
15//  /\s/	Any whitespace character
16//  /./	Any character except newlines
17//  /\b/	A word boundary
18//  /^/	Start of input
19//  /$/	End of input

1const regex = new RegExp('https:\\/\\/\\w*\\.\\w*.*', 'g');

1const match = 'some/path/123'.match(/\/(\d+)/)
2const id = match[1] // '123'

1var r = /^a$/
2
3function matchExact(r, str) {
4   var match = str.match(r);
5   return match && str === match[0];
6}

1const str = 'For more information, see Chapter 3.4.5.1';
2const re = /see (chapter \d+(\.\d)*)/i;
3const found = str.match(re);
4
5console.log(found);
6
7// logs [ 'see Chapter 3.4.5.1',
8//        'Chapter 3.4.5.1',
9//        '.1',
10//        index: 22,
11//        input: 'For more information, see Chapter 3.4.5.1' ]
12
13// 'see Chapter 3.4.5.1' is the whole match.
14// 'Chapter 3.4.5.1' was captured by '(chapter \d+(\.\d)*)'.
15// '.1' was the last value captured by '(\.\d)'.
16// The 'index' property (22) is the zero-based index of the whole match.
17// The 'input' property is the original string that was parsed.