js updates

docs/step1-02/index.html

@@ -5,7 +5,7 @@
     <h1>todos</h1>
     <input class="textfield" placeholder="add todo" /><button class="button add">Add</button>
     <div class="filter">
-      <button class="active">all</button>
+      <button class="selected">all</button>
       <button>active</button>
       <button>completed</button>
     </div>