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Task/Variables/JavaScript/variables.js

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+// a globally-scoped variable
+var a=1;
+
+// global scope
+function one(){
+    alert(a);
+}
+
+// local scope
+function two(a){
+    alert(a);
+}
+
+// local scope again
+function three(){
+  var a = 3;
+  alert(a);
+}
+
+// Intermediate: no such thing as block scope in javascript
+function four(){
+    if(true){
+        var a=4;
+    }
+
+    alert(a); // alerts '4', not the global value of '1'
+}
+
+
+// Intermediate: object properties
+function Five(){
+    this.a = 5;
+}
+
+
+// Advanced: closure
+var six = function(){
+    var foo = 6;
+
+    return function(){
+        // javascript "closure" means I have access to foo in here,
+        // because it is defined in the function in which I was defined.
+        alert(foo);
+    }
+}()
+
+
+// Advanced: prototype-based scope resolution
+function Seven(){
+  this.a = 7;
+}
+
+// [object].prototype.property loses to [object].property in the scope chain
+Seven.prototype.a = -1; // won't get reached, because 'a' is set in the constructor above.
+Seven.prototype.b = 8; // Will get reached, even though 'b' is NOT set in the constructor.
+
+
+
+// These will print 1-8
+one();
+two(2);
+three();
+four();
+alert(new Five().a);
+six();
+alert(new Seven().a);
+alert(new Seven().b);