LeetCode's Baseball Game Challenge

You are keeping the scores for a baseball game with strange rules.
At the beginning of the game, you start with an empty record.

You are given a list of strings operations, where operations[i] is the
ith operation you must apply to the record and is one of the following:
- An integer x.
    - Record a new score of x.
- '+'.
    - Record a new score that is the sum of the previous two scores.
- 'D'.
    - Record a new score that is the double of the previous score.
- 'C'.
    - Invalidate the previous score, removing it from the record.

Return the sum of all the scores on the record after applying all the
operations.

javascript/baseballGame.js

@@ -0,0 +1,64 @@
+/**
+ * Visit https://leetcode.com/problems/baseball-game/description/
+ * for full problem description
+ * 
+ * You are keeping the scores for a baseball game with strange rules. 
+ * At the beginning of the game, you start with an empty record.
+ * 
+ * You are given a list of strings operations, 
+ * where operations[i] is the ith operation you must apply to the record 
+ * and is one of the following:
+ * - An integer x.
+ *  - Record a new score of x.
+ * - '+'.
+ *  - Record a new score that is the sum of the previous two scores.
+ * - 'D'.
+ *  - Record a new score that is the double of the previous score.
+ * - 'C'.
+ *  - Invalidate the previous score, removing it from the record.
+ * 
+ * Return the sum of all the scores on the record 
+ * after applying all the operations.
+ * 
+ * The test cases are generated such that the answer 
+ * and all intermediate calculations fit in a 32-bit integer 
+ * and that all operations are valid.
+ * 
+ * @param {string[]} operations
+ * @return {number}
+ */
+var calPoints = function (operations) {
+    // Start with an empty record
+    const score = [];
+    const length = operations.length;
+
+    for (let i = 0; i < length; i++) {
+        if (operations[i] === '+') {
+            // Record a new score that is the sum of the previous two scores
+            let scoreLength = score.length;
+            score.push(score[scoreLength - 1] + score[scoreLength - 2]);
+        } else if (operations[i] === 'D') {
+            // Record a new score that is the double of the previous score
+            score.push(2 * (score[score.length - 1]));
+        } else if (operations[i] === 'C') {
+            // Invalidate the previous score, removing it from the record
+            score.pop();
+        } else {
+            // Record a new score of x
+            score.push(Number(operations[i]));
+        }
+    }
+
+    // Return the sum of all scores on the record
+    // return score.reduce((total, value) => total + value, 0);
+    // OR
+
+    let sum = 0;
+
+    for (let i = 0; i < score.length; i++) {
+        sum = sum + score[i];
+    }
+
+    return sum;
+
+};