unshift string javascript code example

Example 1: javascript add new array element to start of array

var colors = ["white","blue"];
colors.unshift("red"); //add red to beginning of colors
// colors = ["red","white","blue"]

Example 2: 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 3: 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 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]