updated code chapter 3

Author: loiane

chapter03/01-Stack.js

@@ -1,6 +1,6 @@
 function Stack() {
 
-    var items = [];
+    let items = [];
 
     this.push = function(element){
         items.push(element);

chapter03/01-Stack2.js

@@ -8,33 +8,33 @@ class Stack2 {
 
     push(element){
         this[_items].push(element);
-    };
+    }
 
     pop(){
         return this[_items].pop();
-    };
+    }
 
     peek(){
         return this[_items][this[_items].length-1];
-    };
+    }
 
     isEmpty(){
         return this[_items].length == 0;
-    };
+    }
 
     size(){
         return this[_items].length;
-    };
+    }
 
     clear(){
         this[_items] = [];
-    };
+    }
 
     print(){
-        console.log(this[_items].toString());
-    };
+        console.log(this.toString());
+    }
 
     toString(){
         return this[_items].toString();
-    };
+    }
 }

chapter03/01-Stack3.js

@@ -12,41 +12,40 @@ let Stack3 = (function () {
             let s = items.get(this);
             s.push(element);
             items.set(this, s);
-        };
+        }
 
         pop(){
             let s = items.get(this);
             let r = s.pop();
             items.set(this, s);
             return r;
-        };
+        }
 
         peek(){
             let s = items.get(this);
             return s[s.length-1];
-        };
+        }
 
         isEmpty(){
             return items.get(this).length == 0;
-        };
+        }
 
         size(){
             let s = items.get(this);
             return s.length;
-        };
+        }
 
         clear(){
             items.set(this, []);
-        };
+        }
 
         print(){
-            let s = items.get(this);
             console.log(this.toString());
-        };
+        }
 
         toString(){
             return items.get(this).toString();
-        };
+        }
     }
 
     return Stack3;

chapter03/01-StackES6.js

@@ -0,0 +1,38 @@
+class Stack {
+
+    constructor () {
+        this.items = [];
+    }
+
+    push(element){
+        this.items.push(element);
+    }
+
+    pop(){
+        return this.items.pop();
+    }
+
+    peek(){
+        return this.items[this.items.length-1];
+    }
+
+    isEmpty(){
+        return this.items.length == 0;
+    }
+
+    size(){
+        return this.items.length;
+    }
+
+    clear(){
+        this.items = [];
+    }
+
+    print(){
+        console.log(this.toString());
+    }
+
+    toString(){
+        return this.items.toString();
+    }
+}

chapter03/02-UsingStacks.js

@@ -1,4 +1,4 @@
-var stack = new Stack();
+let stack = new Stack2();
  console.log(stack.isEmpty()); //outputs true
  stack.push(5);
  stack.push(8);
@@ -15,10 +15,10 @@ var stack = new Stack();
 
 //how to ensure true privacy
 //in case using Stack 2 uncomment code below
-/*var objectSymbols = Object.getOwnPropertySymbols(stack);
+let objectSymbols = Object.getOwnPropertySymbols(stack);
 
- console.log(objectSymbols.length); // 2
- console.log(objectSymbols);        // [Symbol(a), Symbol(b)]
- console.log(objectSymbols[0]);     // Symbol(a)
+ console.log(objectSymbols.length); // 1
+ console.log(objectSymbols);        // [Symbol()]
+ console.log(objectSymbols[0]);     // Symbol()
  stack[objectSymbols[0]].push(1);
- stack.print();*/
+ stack.print(); //5, 8, 1

chapter03/03-BalancedSymbols.js

@@ -1,27 +1,30 @@
-function matches(open, close){
-    var opens = "([{",
-        closers = ")]}";
-    return opens.indexOf(open) == closers.indexOf(close);
-}
-
 function parenthesesChecker(symbols){
 
-    var stack = new Stack(),
+    let stack = new Stack(),
         balanced = true,
         index = 0,
-        symbol, top;
+        symbol, top,
+        opens = "([{",
+        closers = ")]}";
 
     while (index < symbols.length && balanced){
         symbol = symbols.charAt(index);
-        if (symbol == '('|| symbol == '[' || symbol == '{'){
+        if (opens.indexOf(symbol) >= 0){
             stack.push(symbol);
+            console.log(`open symbol - stacking ${symbol}`);
         } else {
+            console.log(`close symbol ${symbol}`);
             if (stack.isEmpty()){
                 balanced = false;
+                console.log('Stack is empty, no more symbols to pop and compare');
             } else {
                 top = stack.pop();
-                if (!matches(top, symbol)){
+                //if (!matches(top, symbol)){
+                if (!(opens.indexOf(top) === closers.indexOf(symbol))) {
                     balanced = false;
+                    console.log(`poping symbol ${top} - is not a match compared to ${symbol}`);
+                } else {
+                    console.log(`poping symbol ${top} - is is a match compared to ${symbol}`);
                 }
             }
         }
@@ -33,5 +36,6 @@ function parenthesesChecker(symbols){
     return false;
 }
 
-console.log(parenthesesChecker('{{([][])}()}'));
-console.log(parenthesesChecker('[{()]'));
+console.log(parenthesesChecker('{([])}')); //true
+console.log(parenthesesChecker('{{([][])}()}')); //true
+console.log(parenthesesChecker('[{()]')); //false

chapter03/05-TowerOfHanoi.js

@@ -3,7 +3,7 @@ function towerOfHanoi(n, from, to, helper){
     if (n > 0){
         towerOfHanoi(n-1, from, helper, to);
         to.push(from.pop());
-        console.log('-----')
+        console.log('-----');
         console.log('Source: ' + from.toString());
         console.log('Dest: ' + to.toString());
         console.log('Helper: ' + helper.toString());
@@ -19,7 +19,7 @@ source.push(1);
 var dest = new Stack();
 var helper = new Stack();
 
-towerOfHanoi(3, source, dest, helper);
+towerOfHanoi(source.size(), source, dest, helper);
 
 source.print();
 helper.print();