concat elements in string javascript code example

Example 1: how to concatenate strings javascript

var str1 = "Hello ";
var str2 = "world!";
var res = str1.concat(str2);
// does not change the existing strings, but
// returns a new string containing the text
// of the joined strings.

Example 2: js concat string

const str1 = 'Hello';
const str2 = 'World';

console.log(str1.concat(' ', str2));
// expected output: "Hello World"

console.log(str2.concat(', ', str1));
// expected output: "World, Hello"