how to use a regex in js code example

Example 1: javascript regex

//Declare Reg using slash
let reg = /abc/
//Declare using class, useful for buil a RegExp from a variable
reg = new RegExp('abc')

//Option you must know: i -> Not case sensitive, g -> match all the string
let str = 'Abc abc abc'
str.match(/abc/) //Array(1) ["abc"] match only the first and return
str.match(/abc/g) //Array(2) ["abc","abc"] match all
str.match(/abc/i) //Array(1) ["Abc"] not case sensitive
str.match(/abc/ig) //Array(3) ["Abc","abc","abc"]
//the equivalent with new RegExp is
str.match('abc', 'ig') //Array(3) ["Abc","abc","abc"]

Example 2: javascript regex

// \d	Any digit character
// \w	An alphanumeric character (“word character”)
// \s	Any whitespace character (space, tab, newline, and similar)
// \D	A character that is not a digit
// \W	A nonalphanumeric character
// \S	A nonwhitespace character
// .	Any character except for newline
// /abc/	A sequence of characters
// /[abc]/	Any character from a set of characters
// /[^abc]/	Any character not in a set of characters
// /[0-9]/	Any character in a range of characters
// /x+/	One or more occurrences of the pattern x
// /x+?/	One or more occurrences, nongreedy
// /x*/	Zero or more occurrences
// /x?/	Zero or one occurrence
// /x{2,4}/	Two to four occurrences
// /(abc)/	A group
// /a|b|c/	Any one of several patterns
// /\d/	Any digit character
// /\w/	An alphanumeric character (“word character”)
// /\s/	Any whitespace character
// /./	Any character except newlines
// /\b/	A word boundary
// /^/	Start of input
// /$/	End of input

Example 3: regular expression javascript

// Tests website Regular Expression against document.location (current page url)
if (/^https\:\/\/example\.com\/$/.exec(document.location)){
	console.log("Look mam, I can regex!");
}

Example 4: js regrex

var s = "Please yes\nmake my day!";
s.match(/yes.*day/);
// Returns null
s.match(/yes[^]*day/);
// Returns 'yes\nmake my day'