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* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @flow
*/
'use strict';
import { canUseDOM } from 'fbjs/lib/ExecutionEnvironment';
type Listener = (e: any) => void;
type EventHandle = (target: EventTarget, callback: ?Listener) => () => void;
export type EventOptions = {
capture?: boolean,
passive?: boolean
};
const emptyFunction = () => {};
function supportsPassiveEvents(): boolean {
let supported = false;
// Check if browser supports event with passive listeners
// https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener#Safely_detecting_option_support
Eif (canUseDOM) {
try {
const options = {};
Object.defineProperty(options, 'passive', {
get() {
supported = true;
return false;
}
});
window.addEventListener('test', null, options);
window.removeEventListener('test', null, options);
} catch (e) {}
}
return supported;
}
const canUsePassiveEvents = supportsPassiveEvents();
function getOptions(options: ?EventOptions): EventOptions | boolean {
if (options == null) {
return false;
}
return canUsePassiveEvents ? options : Boolean(options.capture);
}
/**
* Shim generic API compatibility with ReactDOM's synthetic events, without needing the
* large amount of code ReactDOM uses to do this. Ideally we wouldn't use a synthetic
* event wrapper at all.
*/
function isPropagationStopped() {
return this.cancelBubble;
}
function isDefaultPrevented() {
return this.defaultPrevented;
}
function normalizeEvent(event: any) {
event.nativeEvent = event;
event.persist = emptyFunction;
event.isDefaultPrevented = isDefaultPrevented;
event.isPropagationStopped = isPropagationStopped;
return event;
}
/**
*
*/
export default function createEventHandle(type: string, options: ?EventOptions): EventHandle {
const opts = getOptions(options);
return function (target: EventTarget, listener: ?Listener) {
Iif (target == null || typeof target.addEventListener !== 'function') {
throw new Error('createEventHandle: called on an invalid target.');
}
const element = (target: any);
if (listener != null) {
const compatListener = (e) => listener(normalizeEvent(e));
element.addEventListener(type, compatListener, opts);
return function removeListener() {
Eif (element != null) {
element.removeEventListener(type, compatListener, opts);
}
};
} else {
return emptyFunction;
}
};
}
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