Implement Quick Sort in JavaScript

Having worked across sites raking in over 50 billion website visits annually with Higglo Digital I write about tech topics and teach…

Implement Quick Sort in JavaScript

Having worked across sites raking in over 50 billion website visits annually with Higglo Digital I write about tech topics and teach engineers to have solid foundations that will help them get ahead in their career. I also build awesome products for digital nomads — check it out!

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Quick sort is a popular and efficient sorting algorithm that works by dividing and conquering an array of data. It operates by selecting a pivot element from the array and partitioning the other elements into two sub-arrays, according to whether they are less than or greater than the pivot. The sub-arrays are then sorted recursively until the base case of an empty or single-item array is reached, at which point the sort is complete.

To implement quick sort in JavaScript, we can define a function that takes in an array and an optional left and right index, which represent the bounds of the portion of the array that should be sorted. If no left and right indices are provided, we can default them to the start and end of the array.

Here is an example of how this function might look:

// base case: return if the left index is greater than or equal to the right index
if (left >= right) {

// sort the left and right sub-arrays recursively

quickSort(array, pivotIndex + 1, right);

Here is an example of how the partition function might be implemented:

// choose pivot element (we'll use the rightmost element)
const pivot = array[right];

// initialize variables for the left and right indices of the partition

let j = right;

i++; j--;

}
 
// return the final index of the pivot element
return i;
}
To use the quick sort function, we can simply call it with the array that we want to sort:

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Having worked across sites raking in over 50 billion website visits annually with Higglo Digital I write about tech topics and teach…