Roman To Integer

 1 var roman = {
 2     "I": 1,
 3     "V": 5,
 4     "X": 10,
 5     "L": 50,
 6     "C": 100,
 7     "D": 500,
 8     "M": 1000
 9 };
10 
11 var romanToInt = function(s) {
12     if (s.length < 1) {
13         return 0;
14     }
15 
16     for (var i = s.length - 1; i >= 0; i--) {
17         if (i == s.length - 1) {
18             var res = roman[s[i]];
19             continue;
20         }
21 
22         if (roman[s[i]] >= roman[s[i + 1]]) {
23             res += roman[s[i]];
24         } else {
25             res -= roman[s[i]];
26         }
27     }
28 
29     return res;
30 };