short form push assignment for LL stack

Author: shadowcodex

lib/stacks.js

@@ -4,12 +4,11 @@ class LinkedStack {
         this.length = 0;
     }
 
-    push(data) {
-        let node = {
+    push(data) {                
+        this.topNode = {
             value: data,
             prev: this.topNode
         };
-        this.topNode = node;
         this.length++;
         return this.length;        
     }