roman_numerals.js

var out = document.getElementById('out');
for ( var i=1 ; i <=100 ; ++i ) { out.innerHTML+= i+"\t"+romanize(i)+"<br/>"; }
function romanize(num) {
  var lookup = {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},
      roman = '',
      i;
  for ( i in lookup ) {
    while ( num >= lookup[i] ) {
      roman += i;
      num -= lookup[i];
    }
  }
  return roman;
}