string regex in javascript 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 match sequence

// Regular expression match sequence of characters
console.log(/abc/.test("abcde")); // true
console.log(/abc/.test("abxde")); // false

Example 3: javascript regex One or more occurrences of the pattern

// Regular expression 1 or more occurrences of the pattern
console.log(/'\d+'/.test("'123'")); // true
console.log(/'\d+'/.test("''")); // false

let cartoonCrying = /boo+(hoo+)+/i;
console.log(cartoonCrying.test("Boohoooohoohooo"));// true

Example 4: regular expression in javascript

let re = /ab+c/;