up

1-js/06-advanced-functions/03-closure/2-counter-object-independent/solution.md

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+
+Surely it will work just fine.
+
+Both nested functions are created within the same outer Lexical Environment, so they share access to the same `count` variable:
+
+```js run
+function Counter() {
+  let count = 0;
+
+  this.up = function() {
+    return ++count;
+  };
+  
+  this.down = function() {
+    return --count;
+  };
+}
+
+let counter = new Counter();
+
+alert( counter.up() ); // 1
+alert( counter.up() ); // 2
+alert( counter.down() ); // 1
+```

1-js/06-advanced-functions/03-closure/2-counter-object-independent/task.md

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+importance: 5
+
+---
+
+# Counter object
+
+Here a counter object is made with the help of the constructor function.
+
+Will it work? What will it show?
+
+```js
+function Counter() {
+  let count = 0;
+
+  this.up = function() {
+    return ++count;
+  };
+  this.down = function() {
+    return --count;
+  };
+}
+
+let counter = new Counter();
+
+alert( counter.up() ); // ?
+alert( counter.up() ); // ?
+alert( counter.down() ); // ?
+```
+