refactored from ES6 classes to factory function to Stack Data Strucutre

Author: crizstian

04-chapter-Stack/04-chapter-Stacks.js

@@ -1,5 +1,4 @@
 (function (exports) {
-  const stack = require('./stack.module')
-
-  Object.assign(exports, stack)
+  const {stack} = require('./stack.module')
+  Object.assign(exports, {stack})
 }((typeof module.exports !== undefined) ? module.exports : window))

04-chapter-Stack/index.js

@@ -0,0 +1,31 @@
+# Stacks with ES6
+
+### Code Examples
+- [Stack Data Structure](./stack.module.js)
+- [Import Module](./index.js)
+
+### Description
+
+Pattern type: Last item In is the First item Out (LIFO)
+
+![](https://cdn-images-1.medium.com/max/800/0*S3Kr9Cpm16ZmCEad.png)
+
+common operations you can perform on graphs:
+- `push`: adds a new element to the stack
+- `pop`: remove the last item pushed from the stack
+- `peek`: returns the last item pushed to stack
+- `length`: returns the size of the stack
+- `isEmpty`: returns true if the stack has elements or false if it has no elements
+- `getStack`: returns the data of the stack
+
+### Example use case
+- Using the back and forward buttons in your browser
+- dfs search algorithm for graphs search
+- balanced arithmetic operations
+- convert infix to postfix arithmetic operations
+- JS engine uses a stack data structure to execute the algorithms
+
+
+### Resources
+
+- [A Gentle Introduction to Data Structures: How Stacks Work](https://medium.freecodecamp.com/data-structures-stacks-on-stacks-c25f2633c529#.3omw867a9)

04-chapter-Stack/readme.md

@@ -1,26 +1,21 @@
 (function (exports) {
-  let dataStore
-  let top
+  const stack = (data = [], t = 0) => {
+    let dataStore = data
+    let top = t
 
-  const stackFactory = (data = [], t = -1) => {
-    let stackProto = {}
-    dataStore = data
-    top = t
-
-    stackProto.push = (element) => {
-      dataStore[top++] = element
-    }
-
-    stackProto.pop = () => {
-      dataStore.splice(--top, 1)
+    const stackProto = {
+      push (element) {
+        dataStore[top++] = element
+      },
+      pop: () => dataStore.splice(--top, 1),
+      peek: () => dataStore[top - 1],
+      length: () => top,
+      isEmpty: () => top === 0,
+      getStack: () => dataStore
     }
 
-    stackProto.peek = () => dataStore[top - 1]
-
-    stackProto.length = () => top
-
-    stackProto.isEmpty = () => top === -1
+    return Object.create(stackProto)
   }
 
-  Object.assign(exports, {stack: stackFactory})
+  Object.assign(exports, {stack})
 }((typeof module.exports !== undefined) ? module.exports : window))