Fixed formatting and performance for JS problem 150

Author: imaginate

javascript/150-Evaluate-Reverse-Polish-Notation.js

@@ -1,29 +1,25 @@
+/** @const {!Object} */
+const OPERATORS = {
+    '+': (a, b) => a + b,
+    '-': (a, b) => a - b,
+    '*': (a, b) => a * b,
+    '/': (a, b) => Math.trunc(a / b)
+};
+
 /**
  * @param {string[]} tokens
  * @return {number}
  */
- var evalRPN = function(tokens) {
-  let stack = [];
-	for (const token of tokens) {
-		if (/^[+\-*\/]$/.test(token)) {
-      const rhs = stack.pop();
-      const lhs = stack.pop();
-      switch (token) {
-        case '+':
-          stack.push(lhs+rhs);
-          break;
-        case '-':
-          stack.push(lhs-rhs);
-          break;
-        case '*':
-          stack.push(lhs*rhs);
-          break;
-        case '/':
-          stack.push(Math.trunc(lhs/rhs));
-      };
-    } else {
-      stack.push(Number(token));
-    };
-	};
-	return stack.pop();
-};
+function evalRPN(tokens) {
+    const stack = [];
+    for (const token of tokens) {
+        if (token in OPERATORS) {
+            const rhs = stack.pop();
+            const lhs = stack.pop();
+            stack.push(OPERATORS[token](lhs, rhs));
+        } else {
+            stack.push(Number(token));
+        }
+    }
+    return stack.pop();
+}