join two arrays javascript

let arr1 = [0, 1, 2];
let arr2 = [3, 5, 7];
let primes = arr1.concat(arr2);

// > [0, 1, 2, 3, 5, 7]

const array1 = ["Vijendra","Singh"];
const array2 = ["Singh", "Shakya"];
const array3 = [...array1, ...array2];

var array1 = ["Vijendra", "Singh"];
var array2 = ["Singh", "Shakya"];

console.log(array1.concat(array2));

//ES6
const array3 = [...array1, ...array2];

[1,2,3].concat([4,5,6])
// [1,2,3,4,5,6]

const letters = ['a', 'b', 'c'];
const numbers = [1, 2, 3];

letters.concat(numbers);
// result in ['a', 'b', 'c', 1, 2, 3]

//ES6 using the spread operator
const itemsA = [ 'Lightsaber', 'Mockingjay pin', 'Box of chocolates' ];
const itemsB = [ 'Ghost trap', 'The One Ring', 'DeLorean' ]
const allItems = [ ...itemsA, ...itemsB ];

// using push and apply to return the same array
const arr1 = ['a', 'b'];
const arr2 = ['c', 'd'];
arr1.push.apply(arr1, arr2);
console.log(arr1) // ['a', 'b', 'c', 'd']