Number to Roman Number

function convertToRoman(num) {
let str = num.toString();
let index = str.length - 1;
let result = "";
		const numToRoman = [ 
    {1: "I", 2: "II", 3: "III",  4 : "IV", 5: "V", 6: "VI", 7 : "VII", 8 : "VIII", 9 : "IX"}, 
    {1 : "X", 2 : "XX", 3 : "XXX", 4 : "XL", 5 : "L", 6 : "LX", 7 : "LXX", 8 : "LXXX", 9 : "XC"},
    {1 : "C", 2 : "CC", 3 : "CCC", 4 : "CD", 5 : "D", 6 : "DC", 7 : "DCC", 8 : "DCCC", 9 : "CM"},
    {1: "M", 2: "MM", 3: "MMM"}
];

  for (let i = 0; i <= index; i++) {
    if(str[i] === "0") {
      continue;
    };
    result += numToRoman[index - i][str[i]];
  };
return result;
};

Do you think it is useful ?
Is it possible to simplify ?