Roman Numeral Converter

// Roman Numeral Converter
// this function takes a number less than 4,000 as a parameter, and returns the corresponding Roman Numeral 

function convertToRoman(num) {
    // decalare variables for num of thousands, num of hundreds, num of tens, num of ones
    // ex. num = 1999: numThousands = 1, numHundreds = 9, numTens = 9, numOnes = 9 
    const numThousands = Math.floor(num / 1000);
    const numHundreds = Math.floor((num - (numThousands * 1000)) / 100);
    const numTens = Math.floor((num - (numThousands *1000) - (numHundreds * 100)) / 10);
    const numOnes = Math.floor((num - (numThousands *1000) - (numHundreds * 100) - (numTens * 10)) / 1);
    
    // declare a variable to contain Roman Numerals for Thousands
    let strThousands = '';
    // for every thousand, add 'M' to strThousands
    for(let i = 0; i < numThousands; i++) {
        strThousands += 'M';
    }
    
    // decalre a variable to contain Roman Numerals for Hundreds
    let strHundreds = '';
    // assign appropriate Roman Numerals to strHundreds
    if(numHundreds === 5) {
        strHundreds += 'D';
    } else if(numHundreds === 9) {
        strHundreds += 'CM'
    } else if(numHundreds === 4) {
        strHundreds += 'CD';
    } else if(numHundreds > 5 && numHundreds < 9) {
        strHundreds += 'D';
        for(let i = 0; i < (numHundreds - 5); i++) {
            strHundreds += 'C'
        }
    } else if(numHundreds > 0 && numHundreds < 4) {
        for(let i = 0; i < numHundreds; i++) {
            strHundreds += 'C'
        }
    }
    
    // declare a variable to contain Roman Numerals for Tens 
    let strTens = '';
    // assign appropriate Roman Numerals to strTens
    if(numTens === 5) {
        strTens += 'L';
    } else if(numTens === 9) {
        strTens += 'XC';
    } else if(numTens === 4) {
        strTens += 'XL';
    } else if(numTens > 5 && numTens < 9) {
        strTens += 'L';
        for(let i = 0; i < (numTens - 5); i++) {
            strTens += 'X';
        }
    } else if(numTens > 0 && numTens < 4) {
        for(let i = 0; i < numTens; i++) {
            strTens += 'X';
        }
    }

    // decalre a variable to contain Roman Numerals for Ones
    let strOnes = '';
    // assign appropriate Roman Numerals to strOnes
    if(numOnes === 5) {
        strOnes += 'V';
    } else if(numOnes === 9) {
        strOnes += 'IX';
    } else if(numOnes === 4) {
        strOnes += 'IV';
    } else if(numOnes > 5 && numOnes < 9) {
        strOnes += 'V';
        for(let i = 0; i < (numOnes - 5); i++) {
            strOnes += 'I';
        }
    } else if(numOnes > 0 && numOnes < 4) {
        for(let i = 0; i < numOnes; i++) {
            strOnes += 'I';
        }
    }
    
    // return all of the Roman Numeral variables combined into a single string
    return (strThousands + strHundreds + strTens + strOnes);
}