Category: JavaScript

I just spent an hour writing a Radix sort algorithm. It turns out that it is 25% the speed of the built in JavaScript `.sort()` function.

Apparently all this sorting has been figured out in the past. Strange that it’s part of learning to code these days…

const performance = require('perf_hooks').performance;


function getDigit(num, location) {
  let stringNum = num.toString();
  let resultNum = parseInt(stringNum[stringNum.length - 1 - location]);
  if (resultNum) {
    return resultNum;
  } else {
    return 0;
  }
}

function getDigitCount(num) {
  let digitCount =  Math.abs(num).toString().length;
  return digitCount;
}

function mostDigits(arr) {
  let maxDigits = -Infinity;
  for (var i = 0; i < arr.length; i += 1) {
    var digitCount = getDigitCount(arr[i])
    if (maxDigits < digitCount) {
      maxDigits = digitCount;
    }
  }
  return maxDigits;
}

function radixSort(list) {
  let numberOfDigitsTheLargestNumberHas = mostDigits(list);

  for (let i = 0; i < numberOfDigitsTheLargestNumberHas; i += 1) {
    let bucket = [[],[],[],[],[],[],[],[],[]];

    for (var j = 0; j < list.length; j += 1) {
      let number = list[j];
      bucket[getDigit(number, i)].push(number);
    }
    list = bucket.flat(2);
  }
  return list.flat();
}

function sum(a, b) {
  return a - b;
}

var ourBeautifulArray = [50000, 1200,1133, 44, 22, 1, 400000000];
var time1 = performance.now();
console.log(radixSort(ourBeautifulArray));
var time2 = performance.now();
console.log(`RadixSort took ${time2 - time1} to execute`);

var time3 = performance.now();
console.log(ourBeautifulArray.sort(sum));
var time4 = performance.now();
console.log(`Normal JS sort took ${time4 - time3} to execute`);

It’s possible that there is room for improvement in the way I’m executing this algorithm. Perhaps using .flat is causing this.

Either way, even if it’s not a useful thing to be able to do, I think it’s interesting. Once you figure out how it works, it’s neat because it sorts things in non-obvious ways.

I just wish it performed better. LoL

If you want to see the code I’m working with to deepen my knowledge of JavaScript, check out this repository.

This is in response to a FreeCodeCamp curriculum session which teaches spread operators.

I found FCC’s explanation of spread operators (click here) to be a very complex description of a simple concept.

Thank you to Brandon Morrelli’s article which provided a clear description of how spread operators can be used to make it easy to work with arrays.

How the Spread Operator Works

Here is the simple way of understanding how a spread operator works:

var arr1 = ['three', 'four'];

var arr2 = ['one', 'two', ...arr1, 'five', 'six'];

console.log(arr2);
// logs [ 'one', 'two', 'three', 'four', 'five', 'six' ]

Essentially the spread operator allows us to inject arrays into spots where we want only the elements, not the array container.

Here is an example of what happens when we don’t have a spread operator:

var arr1 = ['three', 'four'];

var arr2 = ['one', 'two', arr1, 'five', 'six'];

console.log(arr2);
// logs [ 'one', 'two', [ 'three', 'four' ], 'five', 'six' ]

In the example above, we have a nested array which could be problematic depending on the architecture of your application.

Essentially, this makes it so we can evaluate arrays in place.

ES6: Use the Spread Operator to Evaluate Arrays In-Place

This is the answer that passes the tests in the current version of Free Code Camp:

const arr1 = ['JAN', 'FEB', 'MAR', 'APR', 'MAY'];
let arr2;
(function() {
  "use strict";
  arr2 = [...arr1];
})();
console.log(arr2);