iteration without explicit variable declaration

Signed-off-by: DTrejo <david.trejo@voxer.com>

posts/2011-07-26-iteration-demoralization.md

@@ -0,0 +1,60 @@
+See if you can guess what this will output:
+
+<code>
+    function allNames() {
+      var names = [ 'dan', 'anthony', 'pavel' ];
+      for (name in names) {
+        console.log(name);
+      }
+    }
+
+    allNames();
+</code>
+
+If you guessed this:
+
+> 0<br/>
+> 1<br/>
+> 2<br/>
+
+
+...then you are right! Congratulations!
+
+What you might not have guessed, is what this will output:
+
+<code>
+    console.log(window.name);
+</code>
+
+its:
+
+> "2"
+
+
+Iteration is assignment, and without the use of the `var` keyword, you're really using the `this` object - which in the context of a raw function declaration is the `window` object.
+
+So the original function is equivalent to:
+
+<code>
+    function allNames() {
+      var names = [ 'dan', 'anthony', 'pavel' ];
+      for (this.name in names) {
+        console.log(name);
+      }
+    }
+</code>
+
+Which is also equivalent to:
+
+<code>
+    function allNames() {
+      var names = [ 'dan', 'anthony', 'pavel' ];
+      for (window.name in names) {
+        console.log(name);
+      }
+    }
+</code>
+
+By [@danlash][1]
+
+[1]:https://twitter.com/danlash