Merge pull request jquery#164 from bentonam/129-events-history

added level metadata for issue jquery#129

Author: ajpiano

page/events/history-of-events.md

@@ -1,7 +1,8 @@
 ---
-title   : History of jQuery Events
+title: History of jQuery Events
+level: intermediate
 ---
-Throughout the evolution of jQuery the means of event binding has changed for various reasons ranging from performance to semantics.  As of jQuery v1.7 the `.on()` method is the accepted means of both directly binding events and creating delegated events.  This article aims to explore the history of *event delegation* from jQuery v1.0 - present and how each version leverages it.  
+Throughout the evolution of jQuery the means of event binding has changed for various reasons ranging from performance to semantics.  As of jQuery v1.7 the `.on()` method is the accepted means of both directly binding events and creating delegated events.  This article aims to explore the history of *event delegation* from jQuery v1.0 - present and how each version leverages it.
 
 Given the following html, for our example we want to log the text of the each `<li>` to console whenever it is clicked.
 
@@ -24,7 +25,7 @@ It is possible to use `.bind()` and attach a handler to every element.
 
 ```
 ​$('#list li').bind('click', function(event){
-  console.log( $elem.text() );  
+  console.log( $elem.text() );
 });​​​​​​​​​​​​​​​​​​​​​
 ```
 As discussed in the [event delegation](/event/event-delegation) article, this is not optimal.
@@ -42,7 +43,7 @@ Generally we don't associate `.bind()` with *event delegation*, however prior to
 ​$('#list').bind('click', function(event){
   var $elem = $(event.target);
   if( $elem.is("li") ){
-    console.log( $elem.text() );  
+    console.log( $elem.text() );
   }
 });​​​​​​​​​​​​​​​​​​​​​
 ```
@@ -75,7 +76,7 @@ The last element to recieve the *click* event is *document*, this is where our `
 ### [.live()](http://api.jquery.com/live/) w/ context (Deprecated)
 Introduced in jQuery v1.4
 
-Passing the *context* as a second optional argument to the `$()` function has been supported since v1.0.  However support for using this *context* with the `$.live()` method was not added until v1.4.  
+Passing the *context* as a second optional argument to the `$()` function has been supported since v1.0.  However support for using this *context* with the `$.live()` method was not added until v1.4.
 
 If we were take our previous `.live()` example and provide it the default *context*, it would look like:
 
@@ -100,7 +101,7 @@ In this instance when an `<li>` is clicked the event still bubbles all the way u
 ### [.delegate()](http://api.jquery.com/delegate/) (Deprecated)
 First introduced in jQuery v1.4.2
 
-The `.delegate()` method provides a clear difference between the *context* of where to attach delegated event handler, and the *selector* to match when the event bubbles up to the delegated element. 
+The `.delegate()` method provides a clear difference between the *context* of where to attach delegated event handler, and the *selector* to match when the event bubbles up to the delegated element.
 
 ```
 $('#list').delegate('li', 'click', function(event){
@@ -112,7 +113,7 @@ $('#list').delegate('li', 'click', function(event){
 ### [.on()](http://api.jquery.com/on/)
 First introduced in jQuery v1.7
 
-The `on.()` method gives us a semantic approach for creating directly bound events as well as delegated events.  It eliminates the need to use the deprecated`.bind()`, `.live()` and `.delegate()` methods, providing a single API for creating events. 
+The `on.()` method gives us a semantic approach for creating directly bound events as well as delegated events.  It eliminates the need to use the deprecated`.bind()`, `.live()` and `.delegate()` methods, providing a single API for creating events.
 
 ```
 $('#list').on('click', 'li', function(event){
@@ -122,4 +123,4 @@ $('#list').on('click', 'li', function(event){
 ```
 
 ### Summary
-All of these ways of *event delegation* were innovative and considered a best practice at the time of their release.  Depending on what version of jQuery you have implemented use the appropriate means of *event delegation*. 
+All of these ways of *event delegation* were innovative and considered a best practice at the time of their release.  Depending on what version of jQuery you have implemented use the appropriate means of *event delegation*.