what is unshift function in js code example

Example 1: array.unshift in javascript

//The unshift() method adds one or more elements to the beginning of an array 
//and returns the new length of the array.

const array1 = [1, 2, 3];
console.log(array1.unshift(4, 5));
// expected output: 5
console.log(array1);
// expected output: Array [4, 5, 1, 2, 3]

Example 2: unshift javascript

/*The unshift() adds method elements to the beginning, and push() method 
adds elements to the end of an array.*/
let twentyThree = 'XXIII';
let romanNumerals = ['XXI', 'XXII'];

romanNumerals.unshift('XIX', 'XX');
// now equals ['XIX', 'XX', 'XXI', 'XXII']

romanNumerals.push(twentyThree);
// now equals ['XIX', 'XX', 'XXI', 'XXII', 'XXIII']