JavaScript Algorithms and Data Structures Projects - Roman Numeral Converter

JavaScript
1

Tell us what’s happening:

My code is not producing the desired output for number 4 and numbers greater than 4.

Your code so far

function convertToRoman(num) {
  let numerals = {
    1000: "M",
    900: "CM",
    500: "D",
    400: "CD",
    100: "C",
    90: "XC",
    50: "L",
    40: "XL",
    10: "X",
    9: "IX",
    5: "V",
    4: "IV",
    1: "I"
  };

  let roman = "";
  let decimal = Object.keys(numerals);
  decimal.forEach(key => {
    while(key <= num){
      roman += numerals[key];
      num -= key;
    };
  });
  
  return roman; // Return the Roman numeral string
};
convertToRoman(4);

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36

Challenge Information:

JavaScript Algorithms and Data Structures Projects - Roman Numeral Converter

2

Yes, if you tried to log what your function returns with any number you will see that it returns multiple Is:

console.log(convertToRoman(2));       // II
console.log(convertToRoman(5));       // IIIII
console.log(convertToRoman(10));      // IIIIIIIIII

Your declaration of the numerals object is correct ( Biggest → Smallest ).

BUT, if you tried to log your decimal array you will see this:

[ '1',
  '4',
  '5',
  '9',
  '10',
  '40',
  '50',
  '90',
  '100',
  '400',
  '500',
  '900',
  '1000' ]

As you see, it’s not in the desired order for it to work. That’s because Object.keys() orders them in ascending order.

Try reversing it and see if it works.

3

It worked. Thanks for helping.