array insert index javascript code example

Example 1: 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 2: array insertion javascript

Array.prototype.insert = function ( index, item ) {
    this.splice( index, 0, item );
};

Example 3: javascript add array to array at index

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