adding comments 13. Roman to Integer.js

11-20/13. Roman to Integer.js

@@ -1,32 +1,56 @@
 var romanToInt = function(s) {
-let ans = 0;
+let ans = 0; // ans stores value of roman no.
+// objects are used to refracter the code
+// reducing multiple ifs to single if
 let [obj1,obj2] = [{"I":2,"X":20},{"I":2,"X":20,"C":200}]
+// loop the roman no. string
 for(let i = 0 ; i < s.length;i++){
+    // if I add 1 to ans
     if( s[i] == "I" ){ans += 1}
+    // if V add 5 to ans
     if( s[i] == "V" ){
         ans += 5
+        // if we have IV that means 4 but 
+        // we have already add 1 in previous iteration
+        // we need to subtract 2 to make it 4
         if( s[i-1] == "I" ) {ans -= 2}
     }
+    // if X add 10 to ans
     if( s[i] == "X" ){
         ans += 10
+        // if we have IX that means 9 but 
+        // we have already add 1 in previous iteration
+        // we need to subtract 2 to make it 9
         if( s[i-1] == "I" ) {ans -= 2}
     }
+    // if L add 50 to ans
     if( s[i] == "L" ){
         ans += 50
+        // we check the for any IL or XL combination
+        // subtract the value accordingly
         if(obj1[s[i-1]]){ans -= obj1[s[i-1]]}
     }
+    // if C add 100 to ans
     if( s[i] == "C" ){
         ans += 100
+        // we check the for any IC or XC combination
+        // subtract the value accordingly
         if(obj1[s[i-1]]){ans -= obj1[s[i-1]]}
     }
+    // if D add 500 to ans
     if( s[i] == "D" ){
         ans += 500
+        // we check the for any ID or XD or CD combination
+        // subtract the value accordingly
         if(obj2[s[i-1]]){ans -= obj2[s[i-1]]}
     }
+    // if M add 1000 to ans
     if( s[i] == "M"){
         ans += 1000
+        // we check the for any IM or XM or CM combination
+        // subtract the value accordingly
         if(obj2[s[i-1]]){ans -= obj2[s[i-1]]}
     }
 }
 return ans
-};
+};