an attempt at writing a recursive roman numeral converter that would benefit from tco

recursiveRomanity2.js

var numerals = [1,4,5,9,10,40,50,90,100,400,500,900,1000];
var ohtheromanity = {1: "I", 4: "IV", 5:"V", 9: "IX", 10: "X", 40: "XL", 50: "L", 
                      90: "XC", 100: "C", 400: "CD",  500: "D", 900: "CM", 1000: "M"};

function convert(n,str="") {
 if (n === 0){return str;}
 else {
   var largestInclusiveNumber = numerals.filter(function(x){return x<=n;}).pop();
   var remainder = n -= largestInclusiveNumber;
   return convert(remainder,str.concat(ohtheromanity[largestInclusiveNumber]));
 }
}


convert(1);
//convert(15000000,"");