concat 2 strings in 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: javascript string concat vs +

It is strongly recommended to use the string
concatenationoperators (+, +=) instead of String.concat
method for perfomance reasons

Example 3: concat no and string in javascript

['Hello', ' ', 'World'].join(''); // 'Hello World'

Example 4: how the concat function works javascript

var arr = [1, 2, 3, 4];
var arr2 = [5, 6, 7, 8];

const both = arr.concat(arr2);

console.log(both);
//[1, 2, 3, 4, 5, 6, 7, 8]