Why jQuery add() method seems not to return a jQuery object?
<p>Consider that you want to add an ajax functionality to many links on your page.</p>

<pre><code>&lt;a href='http://domain/purchase/car' class='purchase'&gt;Car&lt;/a&gt;
&lt;a href='http://domain/purchase/bag' class='purchase'&gt;Bag&lt;/a&gt;
&lt;a href='http://domain/purchase/laptop' class='purchase'&gt;Laptop&lt;/a&gt;
</code></pre>

<p>and</p>

<pre><code>&lt;a href='http://domain/sell/car' class='sell'&gt;Car&lt;/a&gt;
&lt;a href='http://domain/sell/bag' class='sell'&gt;Bag&lt;/a&gt;
&lt;a href='http://domain/sell/laptop' class='sell'&gt;Laptop&lt;/a&gt;
</code></pre>

<p>Now you might define some variables to refer to these groups of links in your JavaScript code:</p>

<pre><code>var purchaseLinks = $('.purchase'),
    sellLinks= $('.sell');
</code></pre>

<p>Well, enough story ;). </p>

<p>You can look at the problem in <a href="http://jsfiddle.net/saeedneamati/q573N/" rel="nofollow">this</a> fiddle and <a href="http://jsfiddle.net/saeedneamati/q573N/1/" rel="nofollow">this</a> one.</p>

<p>According to <a href="http://api.jquery.com/add/" rel="nofollow">jQuery's add() documentation</a>, the return value is a <strong>new jQuery object</strong>. And again, AMAIK inside a function handler that is attached to an event of a jQuery object, <code>this</code> referes to the DOM element.</p>

<p>Why by using <code>add()</code> method, <code>this</code> of the handler function refers to the <code>document</code>? I don't understand it. I can't match my knowledge to make a logical perception. In other words:</p>

<pre><code>jQueryObject1.click(function(){
    // Here, $(this) is the jQuery object
});

jQueryObject2.click(function(){
    // Here again, $(this) is the jQuery object
});

jQueryObject1.add(jQueryObject2).click(function(){
    // Here $(this) refers to the Document, why?
    // I think jQueryObject1.add(jQueryObject2) should equal jQueryObject3
});
</code></pre>

<p>UPDATE:</p>

<p>Thanks for your answers. I again refer readers to <a href="http://liveisdeprecated.com/" rel="nofollow">Live is Deprecated</a> page, so that everyone can improve.</p>
