Roman numeral converter solution

Hello @all, this is my solution, with comments. I think could be good for newbies because there's not too much logic and it's a step by step process.
I hope i posted in the right place.

function convertToRoman(num) {
/* convert the number to a string and split it in elements that will be stored in splittedNum array */
let splittedNum = num.toString().split("");

// create arrays for roman numbers entities
let romanMig = [], romanCents = [], romanDecine = [], romanUnits = [];
romanUnits = [ "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX", "X"];
romanDecine = ["X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC", "C" ]
romanCents = ["C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM", "M"];

/* the functions below first extracts the value of the unit (dec , cent, migliaia) from the relative index of the splitted number (array.length - 1 for units, - 2 for dec, - 3 for cents, - 4 for migliaia). 
For example we extract the unit "6" from  "36".
Then we use the number 6 to extract the corresponding roman number (VI) from the array romanUnits []. 
Using 6 as index-1 ( because the array index starts from 0) in the array romanUnits we got romanUnits[5]  and we etract the corresponding element at index 5 > that is VI
In fact index 0 = "I", index 1 = "II",  index 2 = "III", index 3 =  "IV", index 4 = "V", index 5 = "VI", etc...).
Same approach with decine (position in the number is at array.length -2 (in the example with the number 36 we extract  3 from the splittedNum ["3", "6"]  ), 
Then set the code for doing the same with cent (position at -3) and migliaia (position at -4) in case of bigger number provided to the functions.

const findRomanUnit = arr => arr[splittedNum[(splittedNum.length - 1)] -1 ];
const findRomanDecina = arr => arr[splittedNum[(splittedNum.length - 2)] - 1];
const findRomanCents = arr => arr[splittedNum[(splittedNum.length - 3)] - 1]
const findRomanMig = arr => arr[splittedNum[(splittedNum.length - 4)]- 1];

// synthetize the above code 
const migliaia = findRomanMig(romanMig);
const cen = findRomanCents(romanCents);
const dec = findRomanDecina(romanDecine);
const un = findRomanUnit(romanUnits);

// we build our array model for the roman number, based on position of the values
let romanNum = [migliaia, cen, dec, un];

/* now we create a function to eliminate elements that throw undefined from our array, for example numbers like 2014, having a zero inside, can throw undefined for the cents

function eliminaUndef (arr) {
    let newArr = arr.filter(el => el !== undefined);
    return newArr.join("").toString();      

let result = eliminaUndef(romanNum);
return result;



Hope it helps, Bye

as it seems you want to contribute to the guide I am moving your post to a new topic

Hello there.

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Gotcha (i think) Thank You : )

I like your solution. It makes sense to me, and I think it’s better than what I managed to come up with.

Silly question, but why does it say I created this topic when it was created by someone else?

I am unsure, but could be one of the following:

  • This topic was created by a moderator splitting a reply from another topic. If you created the original topic, this could be residual.
  • A previous post you created and read caused that state. Now, when you came here, the state did not update correctly.

Thanks, for pointing it out.

Thanks for replying.
As You can see in the first answer, right after the first post of the topic, ieahleen, who is a moderator, replied:

“as it seems you want to contribute to the guide I am moving your post to a new topic”

In fact, originally i posted my solution in the wrong place: in someone else’s topic about the same challenge.
So ieahleen kindly moved my post to a new topic.
Thank You,
have a nice :sunny: day.

thank you
Glad if You share your solution too.