array.unshift() 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 method in javascript
var name = [ "john" ];
name.unshift( "charlie" );
name.unshift( "joseph", "Jane" );
console.log(name);
//Output will be
[" joseph "," Jane ", " charlie ", " john "]
Example 3: javascript unshift
let array = ["A", "B"];
let variable = "what you want to add";
//Add the variable to the beginning of the array
array.unshift(variable);
//===========================
console.log(array);
//output =>
//["what you want to add" ,"A", "B"]
Example 4: insert element at beginning of array javascript
// Use unshift method if you don't mind mutating issue
// If you want to avoid mutating issue
const array = [3, 2, 1]
const newFirstElement = 4
const newArray = [newFirstElement].concat(array) // [ 4, 3, 2, 1 ]
console.log(newArray);
Example 5: prepend to js array
var a = [1, 2, 3, 4];
a.unshift(0);
a; // => [0, 1, 2, 3, 4]