<p>This method is a shortcut for <code>.bind('keyup', handler)</code> in the first variation, and <code>.trigger('keyup')</code> in the second.</p>
<p>The <code>keyup</code> event is sent to an element when the user releases a key on the keyboard. It can be attached to any element, but the event is only sent to the element that has the focus. Focusable elements can vary between browsers, but form elements can always get focus so are reasonable candidates for this event type.</p>
<p>The event handler can be bound to the input field:</p>
<pre>$('#target').keyup(function() {
alert('Handler for .keyup() called.');
});
</pre>
<p>Now when the insertion point is inside the field and a key is pressed and released, the alert is displayed:</p>
<p><spanclass="output">Handler for .keyup() called.</span></p>
<p>We can trigger the event manually when another element is clicked:</p>
<pre>$('#other').click(function() {
$('#target').keyup();
});</pre>
<p>After this code executes, clicks on <spanclass="output">Trigger the handler</span> will also alert the message.</p>
<p>If key presses anywhere need to be caught (for example, to implement global shortcut keys on a page), it is useful to attach this behavior to the <code>document</code> object. Because of event bubbling, all key presses will make their way up the DOM to the <code>document</code> object unless explicitly stopped.</p>
<p>To determine which key was pressed, we can examine the event object that is passed to the handler function. While browsers use differing attributes to store this information, jQuery normalizes the <code>.which</code> attribute so we can reliably use it to retrieve the key code. This code corresponds to a key on the keyboard, including codes for special keys such as arrows. For catching actual text entry, <code>.keypress()</code> may be a better choice.</p>
