javascript array merge

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

// > [0, 1, 2, 3, 5, 7]//for ES5
var array1 = ["Rahul", "Sachin"];
var array2 = ["Sehwag", "Kohli"];

var output = array1.concat(array2);
console.log(output);

//for ES6, we use spread operators to concat arrays

var array1 = ["Dravid", "Tendulkar"];
var array2 = ["Virendra", "Virat"];

var output = [...array1, ...array2];
console.log(output);
var array1 = ["Vijendra", "Singh"];
var array2 = ["Singh", "Shakya"];

console.log(array1.concat(array2));
// output: ["Vijendra", "Singh", "Singh", "Shakya"]//ES6
const array3 = [...array1, ...array2];const letters = ['a', 'b', 'c'];
const numbers = [1, 2, 3];

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

Also in JavaScript: