1 <p> 2 An <code>Event</code> is an object 3 that allows you to be notified 4 when something interesting happens. 5 Here's an example of using the 6 <code>chrome.tabs.onCreated</code> event 7 to be notified whenever there's a new tab: 8 </p> 9 10 <pre> 11 chrome.tabs.onCreated.<b>addListener(function(</b>tab<b>) {</b> 12 appendToLog('tabs.onCreated --' 13 + ' window: ' + tab.windowId 14 + ' tab: ' + tab.id 15 + ' index: ' + tab.index 16 + ' url: ' + tab.url); 17 <b>});</b> 18 </pre> 19 20 <p> 21 As the example shows, 22 you register for notification using <code>addListener()</code>. 23 The argument to <code>addListener()</code> 24 is always a function that you define to handle the event, 25 but the parameters to the function depend on 26 which event you're handling. 27 Checking the documentation for 28 <a href="tabs.html#event-onCreated"><code>chrome.tabs.onCreated</code></a>, 29 you can see that the function has a single parameter: 30 a <a href="tabs.html#type-Tab">Tab</a> object 31 that has details about the newly created tab. 32 </p> 33 34 <h2> 35 Methods 36 </h2> 37 38 <p> 39 You can invoke the following methods on any <code>Event</code> object: 40 </p> 41 42 <pre> 43 void addListener(function callback(...)) 44 void removeListener(function callback(...)) 45 bool hasListener(function callback(...)) 46 </pre> 47 48 <!-- [PENDING: explain removeListener and hasListener] --> 49
