[LeetCode][JavaScript]Plus One

 1 /**
 2  * @param {number[]} digits
 3  * @return {number[]}
 4  */
 5 var plusOne = function(digits) {
 6     var carry = 1;
 7     for(var i = digits.length - 1; i >= 0; i--){
 8         var sum = digits[i] + carry;
 9         if(sum === 10){
10             digits[i] = 0;
11             carry = 1;
12         }else{
13             digits[i] = sum;
14             carry = 0;
15         }
16     }
17     if(carry === 1){
18         digits.unshift(1);
19     }
20     return digits;
21 };