/**
* @file events.js. An Event System (John Resig - Secrets of a JS Ninja http://jsninja.com/)
* (Original book version wasn't completely usable, so fixed some things and made Closure Compiler compatible)
* This should work very similarly to jQuery's events, however it's based off the book version which isn't as
* robust as jquery's, so there's probably some differences.
*
* @file events.js
* @module events
*/
import DomData from './dom-data';
import * as Guid from './guid.js';
import log from './log.js';
import window from 'global/window';
import document from 'global/document';
/**
* Clean up the listener cache and dispatchers
*
* @param {Element|Object} elem
* Element to clean up
*
* @param {string} type
* Type of event to clean up
*/
function _cleanUpEvents(elem, type) {
if (!DomData.has(elem)) {
return;
}
const data = DomData.get(elem);
// Remove the events of a particular type if there are none left
if (data.handlers[type].length === 0) {
delete data.handlers[type];
// data.handlers[type] = null;
// Setting to null was causing an error with data.handlers
// Remove the meta-handler from the element
if (elem.removeEventListener) {
elem.removeEventListener(type, data.dispatcher, false);
} else if (elem.detachEvent) {
elem.detachEvent('on' + type, data.dispatcher);
}
}
// Remove the events object if there are no types left
if (Object.getOwnPropertyNames(data.handlers).length <= 0) {
delete data.handlers;
delete data.dispatcher;
delete data.disabled;
}
// Finally remove the element data if there is no data left
if (Object.getOwnPropertyNames(data).length === 0) {
DomData.delete(elem);
}
}
/**
* Loops through an array of event types and calls the requested method for each type.
*
* @param {Function} fn
* The event method we want to use.
*
* @param {Element|Object} elem
* Element or object to bind listeners to
*
* @param {string[]} types
* Type of event to bind to.
*
* @param {Function} callback
* Event listener.
*/
function _handleMultipleEvents(fn, elem, types, callback) {
types.forEach(function(type) {
// Call the event method for each one of the types
fn(elem, type, callback);
});
}
/**
* Fix a native event to have standard property values
*
* @param {Object} event
* Event object to fix.
*
* @return {Object}
* Fixed event object.
*/
export function fixEvent(event) {
if (event.fixed_) {
return event;
}
function returnTrue() {
return true;
}
function returnFalse() {
return false;
}
// Test if fixing up is needed
// Used to check if !event.stopPropagation instead of isPropagationStopped
// But native events return true for stopPropagation, but don't have
// other expected methods like isPropagationStopped. Seems to be a problem
// with the Javascript Ninja code. So we're just overriding all events now.
if (!event || !event.isPropagationStopped || !event.isImmediatePropagationStopped) {
const old = event || window.event;
event = {};
// Clone the old object so that we can modify the values event = {};
// IE8 Doesn't like when you mess with native event properties
// Firefox returns false for event.hasOwnProperty('type') and other props
// which makes copying more difficult.
// TODO: Probably best to create an allowlist of event props
const deprecatedProps = [
'layerX', 'layerY', 'keyLocation', 'path',
'webkitMovementX', 'webkitMovementY', 'mozPressure', 'mozInputSource'
];
for (const key in old) {
// Safari 6.0.3 warns you if you try to copy deprecated layerX/Y
// Chrome warns you if you try to copy deprecated keyboardEvent.keyLocation
// and webkitMovementX/Y
// Lighthouse complains if Event.path is copied
if (!deprecatedProps.includes(key)) {
// Chrome 32+ warns if you try to copy deprecated returnValue, but
// we still want to if preventDefault isn't supported (IE8).
if (!(key === 'returnValue' && old.preventDefault)) {
event[key] = old[key];
}
}
}
// The event occurred on this element
if (!event.target) {
event.target = event.srcElement || document;
}
// Handle which other element the event is related to
if (!event.relatedTarget) {
event.relatedTarget = event.fromElement === event.target ?
event.toElement :
event.fromElement;
}
// Stop the default browser action
event.preventDefault = function() {
if (old.preventDefault) {
old.preventDefault();
}
event.returnValue = false;
old.returnValue = false;
event.defaultPrevented = true;
};
event.defaultPrevented = false;
// Stop the event from bubbling
event.stopPropagation = function() {
if (old.stopPropagation) {
old.stopPropagation();
}
event.cancelBubble = true;
old.cancelBubble = true;
event.isPropagationStopped = returnTrue;
};
event.isPropagationStopped = returnFalse;
// Stop the event from bubbling and executing other handlers
event.stopImmediatePropagation = function() {
if (old.stopImmediatePropagation) {
old.stopImmediatePropagation();
}
event.isImmediatePropagationStopped = returnTrue;
event.stopPropagation();
};
event.isImmediatePropagationStopped = returnFalse;
// Handle mouse position
if (event.clientX !== null && event.clientX !== undefined) {
const doc = document.documentElement;
const body = document.body;
event.pageX = event.clientX +
(doc && doc.scrollLeft || body && body.scrollLeft || 0) -
(doc && doc.clientLeft || body && body.clientLeft || 0);
event.pageY = event.clientY +
(doc && doc.scrollTop || body && body.scrollTop || 0) -
(doc && doc.clientTop || body && body.clientTop || 0);
}
// Handle key presses
event.which = event.charCode || event.keyCode;
// Fix button for mouse clicks:
// 0 == left; 1 == middle; 2 == right
if (event.button !== null && event.button !== undefined) {
// The following is disabled because it does not pass videojs-standard
// and... yikes.
/* eslint-disable */
event.button = (event.button & 1 ? 0 :
(event.button & 4 ? 1 :
(event.button & 2 ? 2 : 0)));
/* eslint-enable */
}
}
event.fixed_ = true;
// Returns fixed-up instance
return event;
}
/**
* Whether passive event listeners are supported
*/
let _supportsPassive;
const supportsPassive = function() {
if (typeof _supportsPassive !== 'boolean') {
_supportsPassive = false;
try {
const opts = Object.defineProperty({}, 'passive', {
get() {
_supportsPassive = true;
}
});
window.addEventListener('test', null, opts);
window.removeEventListener('test', null, opts);
} catch (e) {
// disregard
}
}
return _supportsPassive;
};
/**
* Touch events Chrome expects to be passive
*/
const passiveEvents = [
'touchstart',
'touchmove'
];
/**
* Add an event listener to element
* It stores the handler function in a separate cache object
* and adds a generic handler to the element's event,
* along with a unique id (guid) to the element.
*
* @param {Element|Object} elem
* Element or object to bind listeners to
*
* @param {string|string[]} type
* Type of event to bind to.
*
* @param {Function} fn
* Event listener.
*/
export function on(elem, type, fn) {
if (Array.isArray(type)) {
return _handleMultipleEvents(on, elem, type, fn);
}
if (!DomData.has(elem)) {
DomData.set(elem, {});
}
const data = DomData.get(elem);
// We need a place to store all our handler data
if (!data.handlers) {
data.handlers = {};
}
if (!data.handlers[type]) {
data.handlers[type] = [];
}
if (!fn.guid) {
fn.guid = Guid.newGUID();
}
data.handlers[type].push(fn);
if (!data.dispatcher) {
data.disabled = false;
data.dispatcher = function(event, hash) {
if (data.disabled) {
return;
}
event = fixEvent(event);
const handlers = data.handlers[event.type];
if (handlers) {
// Copy handlers so if handlers are added/removed during the process it doesn't throw everything off.
const handlersCopy = handlers.slice(0);
for (let m = 0, n = handlersCopy.length; m < n; m++) {
if (event.isImmediatePropagationStopped()) {
break;
} else {
try {
handlersCopy[m].call(elem, event, hash);
} catch (e) {
log.error(e);
}
}
}
}
};
}
if (data.handlers[type].length === 1) {
if (elem.addEventListener) {
let options = false;
if (supportsPassive() &&
passiveEvents.indexOf(type) > -1) {
options = {passive: true};
}
elem.addEventListener(type, data.dispatcher, options);
} else if (elem.attachEvent) {
elem.attachEvent('on' + type, data.dispatcher);
}
}
}
/**
* Removes event listeners from an element
*
* @param {Element|Object} elem
* Object to remove listeners from.
*
* @param {string|string[]} [type]
* Type of listener to remove. Don't include to remove all events from element.
*
* @param {Function} [fn]
* Specific listener to remove. Don't include to remove listeners for an event
* type.
*/
export function off(elem, type, fn) {
// Don't want to add a cache object through getElData if not needed
if (!DomData.has(elem)) {
return;
}
const data = DomData.get(elem);
// If no events exist, nothing to unbind
if (!data.handlers) {
return;
}
if (Array.isArray(type)) {
return _handleMultipleEvents(off, elem, type, fn);
}
// Utility function
const removeType = function(el, t) {
data.handlers[t] = [];
_cleanUpEvents(el, t);
};
// Are we removing all bound events?
if (type === undefined) {
for (const t in data.handlers) {
if (Object.prototype.hasOwnProperty.call(data.handlers || {}, t)) {
removeType(elem, t);
}
}
return;
}
const handlers = data.handlers[type];
// If no handlers exist, nothing to unbind
if (!handlers) {
return;
}
// If no listener was provided, remove all listeners for type
if (!fn) {
removeType(elem, type);
return;
}
// We're only removing a single handler
if (fn.guid) {
for (let n = 0; n < handlers.length; n++) {
if (handlers[n].guid === fn.guid) {
handlers.splice(n--, 1);
}
}
}
_cleanUpEvents(elem, type);
}
/**
* Trigger an event for an element
*
* @param {Element|Object} elem
* Element to trigger an event on
*
* @param {EventTarget~Event|string} event
* A string (the type) or an event object with a type attribute
*
* @param {Object} [hash]
* data hash to pass along with the event
*
* @return {boolean|undefined}
* Returns the opposite of `defaultPrevented` if default was
* prevented. Otherwise, returns `undefined`
*/
export function trigger(elem, event, hash) {
// Fetches element data and a reference to the parent (for bubbling).
// Don't want to add a data object to cache for every parent,
// so checking hasElData first.
const elemData = DomData.has(elem) ? DomData.get(elem) : {};
const parent = elem.parentNode || elem.ownerDocument;
// type = event.type || event,
// handler;
// If an event name was passed as a string, creates an event out of it
if (typeof event === 'string') {
event = {type: event, target: elem};
} else if (!event.target) {
event.target = elem;
}
// Normalizes the event properties.
event = fixEvent(event);
// If the passed element has a dispatcher, executes the established handlers.
if (elemData.dispatcher) {
elemData.dispatcher.call(elem, event, hash);
}
// Unless explicitly stopped or the event does not bubble (e.g. media events)
// recursively calls this function to bubble the event up the DOM.
if (parent && !event.isPropagationStopped() && event.bubbles === true) {
trigger.call(null, parent, event, hash);
// If at the top of the DOM, triggers the default action unless disabled.
} else if (!parent && !event.defaultPrevented && event.target && event.target[event.type]) {
if (!DomData.has(event.target)) {
DomData.set(event.target, {});
}
const targetData = DomData.get(event.target);
// Checks if the target has a default action for this event.
if (event.target[event.type]) {
// Temporarily disables event dispatching on the target as we have already executed the handler.
targetData.disabled = true;
// Executes the default action.
if (typeof event.target[event.type] === 'function') {
event.target[event.type]();
}
// Re-enables event dispatching.
targetData.disabled = false;
}
}
// Inform the triggerer if the default was prevented by returning false
return !event.defaultPrevented;
}
/**
* Trigger a listener only once for an event.
*
* @param {Element|Object} elem
* Element or object to bind to.
*
* @param {string|string[]} type
* Name/type of event
*
* @param {Event~EventListener} fn
* Event listener function
*/
export function one(elem, type, fn) {
if (Array.isArray(type)) {
return _handleMultipleEvents(one, elem, type, fn);
}
const func = function() {
off(elem, type, func);
fn.apply(this, arguments);
};
// copy the guid to the new function so it can removed using the original function's ID
func.guid = fn.guid = fn.guid || Guid.newGUID();
on(elem, type, func);
}
/**
* Trigger a listener only once and then turn if off for all
* configured events
*
* @param {Element|Object} elem
* Element or object to bind to.
*
* @param {string|string[]} type
* Name/type of event
*
* @param {Event~EventListener} fn
* Event listener function
*/
export function any(elem, type, fn) {
const func = function() {
off(elem, type, func);
fn.apply(this, arguments);
};
// copy the guid to the new function so it can removed using the original function's ID
func.guid = fn.guid = fn.guid || Guid.newGUID();
// multiple ons, but one off for everything
on(elem, type, func);
}