Update 0304-range-sum-query-2d-immutable.js

Converted to Class based.

Author: aadil42

javascript/0304-range-sum-query-2d-immutable.js

@@ -1,30 +1,33 @@
 /**
  * https://leetcode.com/problems/range-sum-query-2d-immutable/
+ * @class NumMatrix
  * @param {number[][]} matrix
  */
- var NumMatrix = function(matrix) {
+class NumMatrix {
+  constructor(matrix) {
     this.matrix = matrix;
-};
+  }
 
-/** 
- * 
- * m = row2 - row1; n = col2 - col1
- * Time O(m*n) | Space O(1)
- * @param {number} row1 
- * @param {number} col1 
- * @param {number} row2 
- * @param {number} col2
- * @return {number}
- */
-NumMatrix.prototype.sumRegion = function(row1, col1, row2, col2) {
+  /** 
+   * 
+   * m = row2 - row1; n = col2 - col1
+   * Time O(m*n) | Space O(1)
+   * @param {number} row1 
+   * @param {number} col1 
+   * @param {number} row2 
+   * @param {number} col2
+   * @return {number}
+   */
+  sumRegion(row1, col1, row2, col2) {
     let sum = 0;
-    for(let i = row1; i < row2 + 1; i++) {
-        for(let j = col1; j < col2 + 1; j++) {
-            sum += this.matrix[i][j];
-        }
+    for (let i = row1; i < row2 + 1; i++) {
+      for (let j = col1; j < col2 + 1; j++) {
+        sum += this.matrix[i][j];
+      }
     }
     return sum;
-};
+  }
+}
 
 /** 
  * Your NumMatrix object will be instantiated and called as such: