Events and Gestures
Many classes have shortcut names used when creating (instantiating) a class with a
configuration object. The shortcut name is referred to as an alias (or xtype if the
class extends Ext.Component). The alias/xtype is listed next to the class name of
applicable classes for quick reference.
Framework classes or their members may be specified as private or protected. Else,
the class / member is public. Public, protected, and private are access
descriptors used to convey how and when the class or class member should be used.
Public classes and class members are available for use by any other class or application code and may be relied upon as a stable and persistent within major product versions. Public classes and members may safely be extended via a subclass.
Protected class members are stable public members intended to be used by the
owning class or its subclasses. Protected members may safely be extended via a subclass.
Private classes and class members are used internally by the framework and are not intended to be used by application developers. Private classes and members may change or be omitted from the framework at any time without notice and should not be relied upon in application logic.
static label next to the
method name. *See Static below.Below is an example class member that we can disect to show the syntax of a class member (the lookupComponent method as viewed from the Ext.button.Button class in this case).
Let's look at each part of the member row:
lookupComponent in this example)( item ) in this example)Ext.Component in this case). This may be omitted for methods that do not
return anything other than undefined or may display as multiple possible values
separated by a forward slash / signifying that what is returned may depend on the
results of the method call (i.e. a method may return a Component if a get method calls is
successful or false if unsuccessful which would be displayed as
Ext.Component/Boolean).PROTECTED in
this example - see the Flags section below)Ext.container.Container in this example). The source
class will be displayed as a blue link if the member originates from the current class
and gray if it is inherited from an ancestor or mixed-in class.view source in the example)item : Object in the example).undefined a "Returns" section
will note the type of class or object returned and a description (Ext.Component in the
example)Available since 3.4.0 - not pictured in
the example) just after the member descriptionDefaults to: false)The API documentation uses a number of flags to further commnicate the class member's function and intent. The label may be represented by a text label, an abbreviation, or an icon.
classInstance.method1().method2().etc();false is returned from
an event handler- Indicates a framework class
- A singleton framework class. *See the singleton flag for more information
- A component-type framework class (any class within the Ext JS framework that extends Ext.Component)
- Indicates that the class, member, or guide is new in the currently viewed version
- Indicates a class member of type config
- Indicates a class member of type property
- Indicates a class member of type
method
- Indicates a class member of type event
- Indicates a class member of type
theme variable
- Indicates a class member of type
theme mixin
- Indicates that the class, member, or guide is new in the currently viewed version
Just below the class name on an API doc page is a row of buttons corresponding to the types of members owned by the current class. Each button shows a count of members by type (this count is updated as filters are applied). Clicking the button will navigate you to that member section. Hovering over the member-type button will reveal a popup menu of all members of that type for quick navigation.
Getting and setter methods that correlate to a class config option will show up in the methods section as well as in the configs section of both the API doc and the member-type menus just beneath the config they work with. The getter and setter method documentation will be found in the config row for easy reference.
Your page history is kept in localstorage and displayed (using the available real estate) just below the top title bar. By default, the only search results shown are the pages matching the product / version you're currently viewing. You can expand what is displayed by clicking on the button on the right-hand side of the history bar and choosing the "All" radio option. This will show all recent pages in the history bar for all products / versions.
Within the history config menu you will also see a listing of your recent page visits. The results are filtered by the "Current Product / Version" and "All" radio options. Clicking on the button will clear the history bar as well as the history kept in local storage.
If "All" is selected in the history config menu the checkbox option for "Show product details in the history bar" will be enabled. When checked, the product/version for each historic page will show alongside the page name in the history bar. Hovering the cursor over the page names in the history bar will also show the product/version as a tooltip.
Both API docs and guides can be searched for using the search field at the top of the page.
On API doc pages there is also a filter input field that filters the member rows using the filter string. In addition to filtering by string you can filter the class members by access level, inheritance, and read only. This is done using the checkboxes at the top of the page.
The checkbox at the bottom of the API class navigation tree filters the class list to include or exclude private classes.
Clicking on an empty search field will show your last 10 searches for quick navigation.
Each API doc page (with the exception of Javascript primitives pages) has a menu view of metadata relating to that class. This metadata view will have one or more of the following:
Ext.button.Button class has an alternate class name of Ext.Button). Alternate class
names are commonly maintained for backward compatibility.Runnable examples (Fiddles) are expanded on a page by default. You can collapse and expand example code blocks individually using the arrow on the top-left of the code block. You can also toggle the collapse state of all examples using the toggle button on the top-right of the page. The toggle-all state will be remembered between page loads.
Class members are collapsed on a page by default. You can expand and collapse members using the arrow icon on the left of the member row or globally using the expand / collapse all toggle button top-right.
Viewing the docs on narrower screens or browsers will result in a view optimized for a smaller form factor. The primary differences between the desktop and "mobile" view are:
The class source can be viewed by clicking on the class name at the top of an API doc page. The source for class members can be viewed by clicking on the "view source" link on the right-hand side of the member row.
The Components and Classes of Ext JS fire a broad range of events at various points in their lifecycle. Events allow your code to react to changes around your application. They are a key concept within Ext JS.
Events fire whenever something interesting happens to one of your Classes.
For example, when Ext.Component renders to the screen, Ext JS fires an
event after the render completes. We can listen for that event
by configuring a simple listeners object:
In this example, when you click the Preview button, the Panel renders to the screen, followed by the defined alert message. All events fired by a class are listed in the class's API page - for example, Ext.panel.Panel currently has 45 events.
While Ext.Component#event-afterrender is useful in some cases, you may use other events more frequently. For instance, Ext.button.Button fires click events when clicked:
A component may contain as many event listeners as needed. In the following example,
we confound users by calling this.hide() inside our mouseover
listener to hide a Button. We then display the button again a second later.
When this.hide() is called, the Button is hidden and the hide
event fires. The hide event triggers our hide listener,
which waits one second and displays the Button again:
Event listeners are called every time an event is fired, so you can continue hiding and showing the button for as long as you desire.
In previous examples, we passed listeners to the component when the class was
instantiated.
However, If we already have an instance, we can add listeners using the on
function:
You can also specify multiple listeners by using the .on method,
similar to using a listener configuration. The following revisits
the previous example that set the button's visibility with a mouseover event:
Just as we can add listeners at any time, we can also remove them. This time we use
the un function. To remove a listener, we need a reference to its function.
In the previous examples, we passed a function into the listener's
object or the on call. This time, we create the function earlier and link
it into a variable called doSomething, which contains our custom function.
Since we initially pass the new doSomething function into our listeners
object, the code begins as before. With the eventual addition of
an Ext#method-defer function, clicking the button in the first
3 seconds yields an alert message. However, after 3
seconds the listener is removed so nothing happens:
Scope sets the value of this inside your handler function. By default, this is set to the
instance of the class firing the event. This is often, but not always, the functionality
that you want. This functionality allows us to
call this.hide() to hide the button in the
second example earlier in this guide.
In the following example, we create a Button and a Panel. We then listen to the Button's
click event with the handler running in Panel's scope. In order to do this, we need to
pass in an object instead of a handler function. This object contains the function AND
the scope:
You can also use a more verbose declaration if your listeners do not have the same options, or, if you're not into the whole brevity thing.
When you run this example, the value of the click handler's this is a reference to the
Panel. To see
this illustrated, we alert the xtype of the scoped component. When the button is
clicked,
we should see the Panel xtype being alerted.
You may want to listen to one event only once. The event itself might fire any number of times, but we only want to listen to it once. The following codes illustrates this situation:
For events that fire many times in short succession, we can reduce the number of times our
listener is called by using a buffer configuration. In this case our button's click listener is only invoked once every 2 seconds, regardless of how many times you click it:
Firing your own events is done by calling fireEvent with
an event name. In the following example we fire an event called myEvent that passes two
arguments - the button itself and
a random number between 1 and 100:
Once again we used Ext.defer to delay the function that
fires our custom event, this time
by 2 seconds. When the event fires, the myEvent listener
picks up on it and displays the arguments we passed in.
Not every ExtJS component raises every event. However, by targeting the container's element, we can attach many native events to which the component can then listen. In this example, we target Ext.container.Container. Containers do not have a click event. Let's give it one!
Without the second block of code, the container's click listener would not fire. Since we have targeted the container's element and attached a click listener, we have extended the container's event capabilities.
Event normalization is the key to allowing Ext JS 5+ applications to run on touch-screen devices. This normalization occurs behind the scenes and is a simple translation from standard mouse events to their equivalent touch and pointer events.
Pointer events are a w3c standard for dealing with events that target a specific set of coordinates on the screen, regardless of input device (mouse, touch, stylus, etc.)
When your code requests a listener for a mouse event, the framework attaches a similar touch or pointer event as needed. For example, if the application attempts to attach a mousedown listener:
myElement.on('mousedown', someFunction);
The event system translates this to touchstart in the case of a device that supports touch events:
myElement.on('touchstart', someFunction);
Or, pointerdown in the case of a device that supports pointer events:
myElement.on('pointerdown', someFunction);
This translation is in place so that you may achieve tablet and touch-screen support without any additional coding.
In most cases the framework can transition seamlessly between mouse, touch, and pointer input. However, there are a few mouse interactions (such as mouseover) that do not translate easily into touch interactions. Such events will need to be handled on an individual basis and are addressed in a following section.
In addition to standard DOM events, Elements also fire synthesized "gesture" events. Since the Sencha Touch event system forms the basis for the Event System, Sencha Touch users may already be familiar with this concept.
From a browser's perspective, there are 3 primary types of pointer, touch, and mouse events - start, move, and end:
| Event | Touch | Pointer | Mouse |
|---|---|---|---|
| Start | touchstart | pointerdown | mousedown |
| Move | touchmove | pointermove | mousemove |
| Stop | touchend | pointerup |
Upon interpreting the sequence and timing of these events, the framework can synthesize
more complex events such as drag, swipe, longpress, pinch, rotate, and tap.
Ext JS applications can listen for gesture events just like any other event, for example:
Ext.get('myElement').on('longpress', handlerFunction);
The original Sencha Touch gesture system was designed primarily with touch events in mind. By adding full support for pointer and mouse events to the Gesture system, Ext JS 5 allows any gesture to respond to any type of input. This means not only that all gestures can be triggered using touch input, but all single-point gestures (tap, swipe, etc.) can be triggered using a mouse as well. This results in a gesture system that works seamlessly across devices regardless of input type.
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