Learn how to merge two arrays in many different ways. Most of the following work on plain JS or using ES6.

Using Array.concat.

var arr1 = [1, 2, 3];
var arr2 = [4, 5, 6];
var array3 = arr1.concat(arr2);
// > [1, 2, 3, 4, 5, 6]

Using Array spread syntax

var arr1 = [1, 2, 3];
var arr2 = [4, 5, 6];
var array3 = [...arr1, ...arr2];
// > [1, 2, 3, 4, 5, 6]

Using Array.push with Array spread syntax

var arr1 = [1, 2, 3];
var arr2 = [4, 5, 6];
var array3 = arr1.push(...arr2);
// > [1, 2, 3, 4, 5, 6]

Using Array.concat with Array spread syntax

var arr1 = [1, 2, 3];
var arr2 = [4, 5, 6];
var array3 = arr1.concat(...arr2);
// > [1, 2, 3, 4, 5, 6]