Update 0303-range-sum-query-immutable.js

Converted to class based.

javascript/0303-range-sum-query-immutable.js

@@ -1,25 +1,26 @@
 /**
+ * https://leetcode.com/problems/range-sum-query-immutable/
  * @param {number[]} nums
  */
-var NumArray = function(nums) {
- this.arr = nums;
-};
+class NumArray {
+ constructor(nums) {
+ this.arr = nums;
+ }
 
-/** 
- * https://leetcode.com/problems/range-sum-query-immutable/description/
- * Time O(n) | Space O(1)
- * @param {number} left 
- * @param {number} right
- * @return {number}
- */
-NumArray.prototype.sumRange = function(left, right) {
-
- let total = 0;
- for(let i = left; i < right + 1; i++) {
- total += this.arr[i];
+ /** 
+  * Time O(n) | Space O(1)
+  * @param {number} left 
+  * @param {number} right
+  * @return {number}
+  */
+  sumRange(left, right) {
+ let total = 0;
+  for (let i = left; i < right + 1; i++) {
+  total += this.arr[i];
+  }
+ return total;
  }
- return total
-};
+}
 
 /** 
  * Your NumArray object will be instantiated and called as such: