// A very elegant solution, thanks to melih on CodePen
// https://codepen.io/melih193/pen/Wxkqjv

$("button").click(function(){
var num = $('#input-number').val();
var roman = '';

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};

  var i;
  
  for ( i in lookup ) {
    while ( num >= lookup[i] ) {
      roman += i;
      num -= lookup[i];
      console.log(i + ', ' + num + ', ' + lookup[i] + ', ' + roman);
    }
  }

  $("#output").val(roman);
  
});