Insertion sort in JavaScript Implementation Algorithm and Pseudocode

By: Prof. Fazal Rehman Shamil						

Last modified on May 27th, 2019			

Insertion sort in JavaScript Implementation Algorithm and Pseudocode

Here, we are sharing the code f Insertion sort in JavaScript Implementation Algorithm and Pseudocode.

It is a simple sorting algorithm used to arranging the array list in a sequence by using ascending or descending order. Insertion sort is not the best algorithm than selection sort, bubble sort and merge sort in term of performance in practical scenarios.

Algorithm of Insertion sort

Insertion.sort (A)

{

For j=2 to length A.length

Key=A[i]

// insert A[j] into sorted sequence

i= j-1

while (i>0 and A[i]>Key)

A [i+1] = A[i]

i = i-1

A [i=1] = Key

}

i j key=4

1 2 3 4 5 6 indexes

In this case, we consider the j loop first because if you select the first number, then you have to compare this with the second number. So, you can start from 2^nd number. Key=A[i] it means that Key=4, i starts from 1^st number.

Key =4

i=0

Here i= j-1, In this case, I go to 0 and goes to out of the loop.

i j Key =5

By performing A [i=1] = Key, 8 is replaced with 4, and increment in j.

In this step, i goes to left and it takes place at number 8(array index 2) and now you can compare again. i is not greater than key so, you can perform i = i-1 and goes to 0 and then perform A [i=1] = Key and 8 is located as key.

i j Key =3

Now compare again

i Key =3

In this step 8 is overriding and I goes to at number 5

At this stage, i goes to number 4 according to i = i-1

i=0

Now you can compare with key =3 and i goes to 0 according to i = i-1

i j Key =6

In this case, you can again compare i and j, i is greater than 0

In this step, i is not greater than key =6 and it goes out of the loop.

i j Key =7

According to A [i=1] = Key and compare again

Key =7

Implementation of Insertion sort in Javascript

&lt;button onclick="sortbyalphabetically()"&gt;Sort Alpha&lt;/button&gt;
&lt;button onclick="sortbynumerically()"&gt;Sort Num&lt;/button&gt;
&lt;p id="sortresult"&gt;&lt;/p&gt;
&lt;script&gt;
var points = [60, 110, 4, 7, 55, 30];
document.getElementById("sortresult").innerHTML = points;
function sortbyalphabetically() {
points.sort();
document.getElementById("sortresult").innerHTML = points;
}
function sortbynumerically() {
points.sort(function(a, b)
{return a - b}
);
document.getElementById("sortresult").innerHTML = points;
}
&lt;/script&gt;

<button onclick="sortbyalphabetically()">Sort Alpha</button>

var points = [60, 110, 4, 7, 55, 30];

document.getElementById("sortresult").innerHTML = points;

function sortbyalphabetically() {

points.sort();

document.getElementById("sortresult").innerHTML = points;

}

function sortbynumerically() {

points.sort(function(a, b)

{return a - b}

);

document.getElementById("sortresult").innerHTML = points;

}

</script>

Output

Insertion sort in JavaScript Implementation Algorithm and Pseudocode