Keyboard
Extends: EventHandler
A Keyboard device bound to an Element. Allows you to detect the state of the key presses. Note that the Keyboard object must be attached to an Element before it can detect any key presses.
// attach keyboard listeners to the window
const keyboard = new pc.Keyboard(window);
Summary
Methods
attach | Attach the keyboard event handlers to an Element. |
detach | Detach the keyboard event handlers from the element it is attached to. |
isPressed | Return true if the key is currently down. |
wasPressed | Returns true if the key was pressed since the last update. |
wasReleased | Returns true if the key was released since the last update. |
Events
keydown | Fired when a key is pressed. |
keyup | Fired when a key is released. |
Inherited
Methods
fire | Fire an event, all additional arguments are passed on to the event listener. |
hasEvent | Test if there are any handlers bound to an event name. |
off | Detach an event handler from an event. |
on | Attach an event handler to an event. |
once | Attach an event handler to an event. |
Details
Constructor
Keyboard([element], [options])
Create a new Keyboard instance.
// attach keyboard listeners to the window
const keyboard = new pc.Keyboard(window);
Parameters
element | Element, Window | Element to attach Keyboard to. Note that elements like <div> can't accept focus by default. To use keyboard events on an element like this it must have a value of 'tabindex' e.g. tabindex="0". See here for more details. |
options | object | Optional options object. |
options.preventDefault | boolean | Call preventDefault() in key event handlers. This stops the default action of the event occurring. e.g. Ctrl+T will not open a new browser tab. |
options.stopPropagation | boolean | Call stopPropagation() in key event handlers. This stops the event bubbling up the DOM so no parent handlers will be notified of the event. |
Methods
attach(element)
Attach the keyboard event handlers to an Element.
Parameters
element | Element, Window | The element to listen for keyboard events on. |
detach()
Detach the keyboard event handlers from the element it is attached to.
isPressed(key)
Return true if the key is currently down.
Parameters
key | number | The keyCode of the key to test. See the KEY_* constants. |
Returns
booleanTrue if the key was pressed, false if not.
wasPressed(key)
Returns true if the key was pressed since the last update.
Parameters
key | number | The keyCode of the key to test. See the KEY_* constants. |
Returns
booleanTrue if the key was pressed.
wasReleased(key)
Returns true if the key was released since the last update.
Parameters
key | number | The keyCode of the key to test. See the KEY_* constants. |
Returns
booleanTrue if the key was pressed.
Events
keydown
Fired when a key is pressed.
const onKeyDown = function (e) {
if (e.key === pc.KEY_SPACE) {
// space key pressed
}
e.event.preventDefault(); // Use original browser event to prevent browser action.
};
app.keyboard.on("keydown", onKeyDown, this);
Parameters
event | KeyboardEvent | The Keyboard event object. Note, this event is only valid for the current callback. |
keyup
Fired when a key is released.
const onKeyUp = function (e) {
if (e.key === pc.KEY_SPACE) {
// space key released
}
e.event.preventDefault(); // Use original browser event to prevent browser action.
};
app.keyboard.on("keyup", onKeyUp, this);
Parameters
event | KeyboardEvent | The Keyboard event object. Note, this event is only valid for the current callback. |
Inherited
Methods
fire(name, [arg1], [arg2], [arg3], [arg4], [arg5], [arg6], [arg7], [arg8])
Fire an event, all additional arguments are passed on to the event listener.
obj.fire('test', 'This is the message');
Parameters
name | string | Name of event to fire. |
arg1 | * | First argument that is passed to the event handler. |
arg2 | * | Second argument that is passed to the event handler. |
arg3 | * | Third argument that is passed to the event handler. |
arg4 | * | Fourth argument that is passed to the event handler. |
arg5 | * | Fifth argument that is passed to the event handler. |
arg6 | * | Sixth argument that is passed to the event handler. |
arg7 | * | Seventh argument that is passed to the event handler. |
arg8 | * | Eighth argument that is passed to the event handler. |
Returns
EventHandlerSelf for chaining.
hasEvent(name)
Test if there are any handlers bound to an event name.
obj.on('test', function () { }); // bind an event to 'test'
obj.hasEvent('test'); // returns true
obj.hasEvent('hello'); // returns false
Parameters
name | string | The name of the event to test. |
Returns
booleanTrue if the object has handlers bound to the specified event name.
off([name], [callback], [scope])
Detach an event handler from an event. If callback is not provided then all callbacks are unbound from the event, if scope is not provided then all events with the callback will be unbound.
const handler = function () {
};
obj.on('test', handler);
obj.off(); // Removes all events
obj.off('test'); // Removes all events called 'test'
obj.off('test', handler); // Removes all handler functions, called 'test'
obj.off('test', handler, this); // Removes all handler functions, called 'test' with scope this
Parameters
name | string | Name of the event to unbind. |
callback | HandleEventCallback | Function to be unbound. |
scope | object | Scope that was used as the this when the event is fired. |
Returns
EventHandlerSelf for chaining.
on(name, callback, [scope])
Attach an event handler to an event.
obj.on('test', function (a, b) {
console.log(a + b);
});
obj.fire('test', 1, 2); // prints 3 to the console
Parameters
name | string | Name of the event to bind the callback to. |
callback | HandleEventCallback | Function that is called when event is fired. Note the callback is limited to 8 arguments. |
scope | object | Object to use as 'this' when the event is fired, defaults to current this. |
Returns
EventHandlerSelf for chaining.
once(name, callback, [scope])
Attach an event handler to an event. This handler will be removed after being fired once.
obj.once('test', function (a, b) {
console.log(a + b);
});
obj.fire('test', 1, 2); // prints 3 to the console
obj.fire('test', 1, 2); // not going to get handled
Parameters
name | string | Name of the event to bind the callback to. |
callback | HandleEventCallback | Function that is called when event is fired. Note the callback is limited to 8 arguments. |
scope | object | Object to use as 'this' when the event is fired, defaults to current this. |
Returns
EventHandlerSelf for chaining.