Page MenuHomeWickedGov Phorge
Files F4113300

ve.EventSequencer.js
No OneTemporary
Actions

Size
12 KB
Referenced Files
None
Subscribers
None

ve.EventSequencer.js
View Options

/*!
* VisualEditor EventSequencer class.
*
* @copyright See AUTHORS.txt
*/
/**
* EventSequencer class with on-event and after-event listeners.
*
* After-event listeners are fired as soon as possible after the
* corresponding native event. They are similar to the setTimeout(f, 0)
* idiom, except that they are guaranteed to execute before any subsequent
* on-event listener. Therefore, events are executed in the 'right order'.
*
* This matters when many events are added to the task queue in one go.
* For instance, browsers often queue 'keydown' and 'keypress' in immediate
* sequence, so a setTimeout(f, 0) defined in the keydown listener will run
* **after** the keypress listener (i.e. in the 'wrong' order). EventSequencer
* ensures that this does not happen.
*
* All these listeners receive the jQuery event as an argument. If an on-event
* listener needs to pass information to a corresponding after-event listener,
* it can do so by adding properties into the jQuery event itself.
*
* There are also 'onLoop' and 'afterLoop' listeners, which only fire once per
* Javascript event loop iteration, respectively before and after all the
* other listeners fire.
*
* There is special handling for sequences (keydown,keypress), where the
* keypress handler is called before the native keydown action happens. In
* this case, after-keydown handlers fire after on-keypress handlers.
*
* For further event loop / task queue information, see:
* http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#event-loops
*
* @class ve.EventSequencer
*/
/**
* To fire after-event listeners promptly, the EventSequencer may need to
* listen to some events for which it has no registered on-event or
* after-event listeners. For instance, to ensure an after-keydown listener
* is be fired before the native keyup action, you must include both
* 'keydown' and 'keyup' in the eventNames Array.
*
* @constructor
* @param {string[]} eventNames List of event Names to listen to
*/
ve.EventSequencer = function VeEventSequencer( eventNames ) {
this.$node = null;
this.eventNames = eventNames;
this.eventHandlers = {};
/**
* Generate an event handler for a specific event
*
* @private
* @param {string} name The event's name
* @return {Function} An event handler
*/
const makeEventHandler = ( name ) => ( ev ) => this.onEvent( name, ev );
/**
* @property {Object[]} Pending calls
* - id {number} Id for setTimeout
* - func {Function} Post-event listener
* - ev {jQuery.Event} Browser event
* - eventName {string} Name, such as keydown
*/
this.pendingCalls = [];
/**
* @property {Object.<string,Function[]>}
*/
this.onListenersForEvent = {};
/**
* @property {Object.<string,Function[]>}
*/
this.afterListenersForEvent = {};
/**
* @property {Object.<string,Function[]>}
*/
this.afterOneListenersForEvent = {};
for ( let i = 0, len = eventNames.length; i < len; i++ ) {
const eventName = eventNames[ i ];
this.onListenersForEvent[ eventName ] = [];
this.afterListenersForEvent[ eventName ] = [];
this.afterOneListenersForEvent[ eventName ] = [];
this.eventHandlers[ eventName ] = makeEventHandler( eventName );
}
/**
* @property {Function[]}
*/
this.onLoopListeners = [];
/**
* @property {Function[]}
*/
this.afterLoopListeners = [];
/**
* @property {Function[]}
*/
this.afterLoopOneListeners = [];
/**
* @property {boolean}
*/
this.doneOnLoop = false;
/**
* @property {number}
*/
this.afterLoopTimeoutId = null;
};
/**
* Attach to a node, to listen to its jQuery events
*
* @param {jQuery} $node The node to attach to
* @return {ve.EventSequencer}
* @chainable
*/
ve.EventSequencer.prototype.attach = function ( $node ) {
this.detach();
this.$node = $node.on( this.eventHandlers );
return this;
};
// eslint-disable-next-line jsdoc/require-returns-check
/**
* Detach from a node (if attached), to stop listen to its jQuery events
*
* @return {ve.EventSequencer}
* @chainable
*/
ve.EventSequencer.prototype.detach = function () {
if ( this.$node === null ) {
return;
}
this.runPendingCalls();
this.$node.off( this.eventHandlers );
this.$node = null;
return this;
};
/**
* Add listeners to be fired at the start of the Javascript event loop iteration
*
* @param {Function|Function[]} listeners Listener(s) that take no arguments
* @return {ve.EventSequencer}
* @chainable
*/
ve.EventSequencer.prototype.onLoop = function ( listeners ) {
if ( !Array.isArray( listeners ) ) {
listeners = [ listeners ];
}
ve.batchPush( this.onLoopListeners, listeners );
return this;
};
/**
* Add listeners to be fired just before the browser native action
*
* @param {Object.<string,Function>} listeners Function for each event
* @return {ve.EventSequencer}
* @chainable
*/
ve.EventSequencer.prototype.on = function ( listeners ) {
for ( const eventName in listeners ) {
this.onListenersForEvent[ eventName ].push( listeners[ eventName ] );
}
return this;
};
/**
* Add listeners to be fired as soon as possible after the native action
*
* @param {Object.<string,Function>} listeners Function for each event
* @return {ve.EventSequencer}
* @chainable
*/
ve.EventSequencer.prototype.after = function ( listeners ) {
for ( const eventName in listeners ) {
this.afterListenersForEvent[ eventName ].push( listeners[ eventName ] );
}
return this;
};
/**
* Add listeners to be fired once, as soon as possible after the native action
*
* @param {Object.<string,Function[]>} listeners Function for each event
* @return {ve.EventSequencer}
* @chainable
*/
ve.EventSequencer.prototype.afterOne = function ( listeners ) {
for ( const eventName in listeners ) {
this.afterOneListenersForEvent[ eventName ].push( listeners[ eventName ] );
}
return this;
};
/**
* Add listeners to be fired at the end of the Javascript event loop iteration
*
* @param {Function|Function[]} listeners Listener(s) that take no arguments
* @return {ve.EventSequencer}
* @chainable
*/
ve.EventSequencer.prototype.afterLoop = function ( listeners ) {
if ( !Array.isArray( listeners ) ) {
listeners = [ listeners ];
}
ve.batchPush( this.afterLoopListeners, listeners );
return this;
};
/**
* Add listeners to be fired once, at the end of the Javascript event loop iteration
*
* @param {Function|Function[]} listeners Listener(s) that take no arguments
* @return {ve.EventSequencer}
* @chainable
*/
ve.EventSequencer.prototype.afterLoopOne = function ( listeners ) {
if ( !Array.isArray( listeners ) ) {
listeners = [ listeners ];
}
ve.batchPush( this.afterLoopOneListeners, listeners );
return this;
};
/**
* Generic listener method which does the sequencing
*
* @private
* @param {string} eventName Javascript name of the event, e.g. 'keydown'
* @param {jQuery.Event} ev The browser event
*/
ve.EventSequencer.prototype.onEvent = function ( eventName, ev ) {
this.runPendingCalls( eventName );
if ( !this.doneOnLoop ) {
this.doneOnLoop = true;
this.doOnLoop();
}
// Listener list: take snapshot (for immutability if a listener adds another listener)
const onListeners = ( this.onListenersForEvent[ eventName ] || [] ).slice();
for ( let i = 0, len = onListeners.length; i < len; i++ ) {
const onListener = onListeners[ i ];
this.callListener( 'on', eventName, i, onListener, ev );
}
// Create a cancellable pending call. We need one even if there are no after*Listeners, to
// call resetAfterLoopTimeout which resets doneOneLoop to false.
// - Create the pendingCall object first
// - then create the setTimeout invocation to modify pendingCall.id
// - then set pendingCall.id to the setTimeout id, so the call can cancel itself
const pendingCall = { id: null, ev: ev, eventName: eventName };
const id = this.postpone( () => {
if ( pendingCall.id === null ) {
// clearTimeout seems not always to work immediately
return;
}
this.resetAfterLoopTimeout();
pendingCall.id = null;
this.afterEvent( eventName, ev );
} );
pendingCall.id = id;
this.pendingCalls.push( pendingCall );
};
/**
* Generic after listener method which gets queued
*
* @private
* @param {string} eventName Javascript name of the event, e.g. 'keydown'
* @param {jQuery.Event} ev The browser event
*/
ve.EventSequencer.prototype.afterEvent = function ( eventName, ev ) {
// Listener list: take snapshot (for immutability if a listener adds another listener)
const afterListeners = ( this.afterListenersForEvent[ eventName ] || [] ).slice();
// One-time listener list: take snapshot (for immutability) and blank the list
const afterOneListeners = ( this.afterOneListenersForEvent[ eventName ] || [] ).splice( 0 );
for ( let i = 0, len = afterListeners.length; i < len; i++ ) {
this.callListener( 'after', eventName, i, afterListeners[ i ], ev );
}
for ( let i = 0, len = afterOneListeners.length; i < len; i++ ) {
this.callListener( 'afterOne', eventName, i, afterOneListeners[ i ], ev );
}
};
/**
* Call each onLoopListener once
*
* @private
*/
ve.EventSequencer.prototype.doOnLoop = function () {
// Length cache 'len' is required, as the functions called may add another listener
for ( let i = 0, len = this.onLoopListeners.length; i < len; i++ ) {
this.callListener( 'onLoop', null, i, this.onLoopListeners[ i ], null );
}
};
/**
* Call each afterLoopListener once, unless the setTimeout is already cancelled
*
* @private
* @param {number} myTimeoutId The calling setTimeout id
*/
ve.EventSequencer.prototype.doAfterLoop = function ( myTimeoutId ) {
if ( this.afterLoopTimeoutId !== myTimeoutId ) {
// Cancelled; do nothing
return;
}
this.afterLoopTimeoutId = null;
// Loop listener list: take snapshot (for immutability if a listener adds another listener)
const afterLoopListeners = this.afterLoopListeners.slice();
// One-time loop listener list: take snapshot (for immutability) and blank the list
const afterLoopOneListeners = this.afterLoopOneListeners.splice( 0 );
for ( let i = 0, len = afterLoopListeners.length; i < len; i++ ) {
this.callListener( 'afterLoop', null, i, this.afterLoopListeners[ i ], null );
}
for ( let i = 0, len = afterLoopOneListeners.length; i < len; i++ ) {
this.callListener( 'afterLoopOne', null, i, afterLoopOneListeners[ i ], null );
}
this.doneOnLoop = false;
};
/**
* Push any pending doAfterLoop to end of task queue (cancel, then re-set)
*
* @private
*/
ve.EventSequencer.prototype.resetAfterLoopTimeout = function () {
if ( this.afterLoopTimeoutId !== null ) {
this.cancelPostponed( this.afterLoopTimeoutId );
}
const timeoutId = this.postpone( () => {
this.doAfterLoop( timeoutId );
} );
this.afterLoopTimeoutId = timeoutId;
};
/**
* Run any pending listeners, and clear the pending queue
*
* @private
* @param {string} eventName The name of the event currently being triggered
*/
ve.EventSequencer.prototype.runPendingCalls = function ( eventName ) {
const afterKeyDownCalls = [];
for ( let i = 0; i < this.pendingCalls.length; i++ ) {
// Length cache not possible, as a pending call appends another pending call.
// It's important that this list remains mutable, in the case that this
// function indirectly recurses.
const pendingCall = this.pendingCalls[ i ];
if ( pendingCall.id === null ) {
// The call has already run
continue;
}
if ( eventName === 'keypress' && pendingCall.eventName === 'keydown' ) {
// Delay afterKeyDown till after keypress
afterKeyDownCalls.push( pendingCall );
continue;
}
this.cancelPostponed( pendingCall.id );
pendingCall.id = null;
// Force to run now. It's important that we set id to null before running,
// so that there's no chance a recursive call will call the listener again.
this.afterEvent( pendingCall.eventName, pendingCall.ev );
}
// This is safe: we only ever appended to the list, so it's definitely exhausted now.
this.pendingCalls.length = 0;
this.pendingCalls.push.apply( this.pendingCalls, afterKeyDownCalls );
};
/**
* Make a postponed call.
*
* This is a separate function because that makes it easier to replace when testing
*
* @param {Function} callback The function to call
* @return {number} Unique postponed timeout id
*/
ve.EventSequencer.prototype.postpone = function ( callback ) {
return setTimeout( callback );
};
/**
* Cancel a postponed call.
*
* This is a separate function because that makes it easier to replace when testing
*
* @param {number} timeoutId Unique postponed timeout id
*/
ve.EventSequencer.prototype.cancelPostponed = function ( timeoutId ) {
clearTimeout( timeoutId );
};
/**
* Single method to perform all listener calls, for ease of debugging
*
* @param {string} timing on|after|afterOne|onLoop|afterLoop|afterLoopOne
* @param {string} eventName Name of the event
* @param {number} i The sequence of the listener
* @param {Function} listener The listener to call
* @param {jQuery.Event} ev The browser event
*/
ve.EventSequencer.prototype.callListener = function ( timing, eventName, i, listener, ev ) {
listener( ev );
};

File Metadata

Mime Type
text/plain
Expires
Tue, Aug 18, 23:20 (1 d, 14 h)
Storage Engine
local-disk
Storage Format
Raw Data
Storage Handle
e8/92/1efaafed0b4b767babb56a736894
Default Alt Text
ve.EventSequencer.js (12 KB)

Event Timeline