Convert numbers to roman numerals using for loop

Tell us what’s happening:
Describe your issue in detail here.
I’d like some feedback in my solution to make it more efficient using for loop or to improve my code.

``````   **Your code so far**
``````
``````
function convertToRoman(num) {
//values of the numbers
let numerals = {
M: 1000,
CM: 900,
D: 500,
CD: 400,
C: 100,
XC: 90,
L: 50,
XL: 40,
X: 10,
IX: 9,
V: 5,
IV: 4,
I: 1,
};
//passing the new values of the new numbers to convert into numerals
let newNumeral = "";
let numCopy = num;   //copy the num so it doesn't mutate and can used inside the for loop

//checking the values of numerals objects
for (let i in numerals) {
//using the j variable of num, if the num is still greater than the numerals index
//it will increment the key to the variable newNumerals and stop the loop,
// it will subtract the num to the values of numerals .
for (let j= 0; j <= num; j++ ){
if(numCopy >= numerals[i]) {
newNumeral += i;
numCopy -= numerals[i];
}
}
}
return newNumeral;
}

console.log(convertToRoman(8));
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``````   **Your browser information:**
``````

User Agent is: `Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4758.109 Safari/537.36`

Challenge: Roman Numeral Converter