array insertion javascript

function insertionSort(inputArr) {
    let n = inputArr.length;
        for (let i = 1; i < n; i++) {
            // Choosing the first element in our unsorted subarray
            let current = inputArr[i];
            // The last element of our sorted subarray
            let j = i-1; 
            while ((j > -1) && (current < inputArr[j])) {
                inputArr[j+1] = inputArr[j];
                j--;
            }
            inputArr[j+1] = current;
        }
    return inputArr;
}

var list = ["foo", "bar"];


list.push("baz");


["foo", "bar", "baz"] // result

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

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits;

function myFunction() {
  fruits.splice(2, 0, "Lemon", "Kiwi");
  document.getElementById("demo").innerHTML = fruits;
}