javascript insert to array at index code example

Example 1: javascript insert item into array

var colors=["red","blue"];
var index=1;

//insert "white" at index 1
colors.splice(index, 0, "white");   //colors =  ["red", "white", "blue"]

Example 2: add element to array using splice

//we can add elements to array using splice

const strings=['a','b','c','d']

//go the 2nd index,remove 0 elements and then add 'alien' to it
strings.splice(2,0,'alien')

console.log(strings) //["a", "b", "alien", "c", "d"]

//what is the time complexity ???
//worst case is O(n). if we are adding to end of array then O(1)
//in our example we added to the middle of array so O(n/2)=>O(n)

Example 3: insert item into array specific index javascript

myArray.splice(index, 0, item);

Example 4: javascript add array to array at index

a1.splice(2, 0, ...a2);