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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
/**
* Methods for setting up and tearing down page event listeners. These are used
* to dismiss Feature Callouts when the callout's anchor element is clicked.
*/
export class PageEventManager {
/**
* A set of parameters defining a page event listener.
* @typedef {Object} PageEventListenerParams
* @property {String} type Event type string e.g. `click`
* @property {String} [selectors] Target selector, e.g. `tag.class, #id[attr]`
* @property {PageEventListenerOptions} [options] addEventListener options
*
* @typedef {Object} PageEventListenerOptions
* @property {Boolean} [capture] Use event capturing phase?
* @property {Boolean} [once] Remove listener after first event?
* @property {Boolean} [preventDefault] Inverted value for `passive` option
* @property {Number} [interval] Used only for `timeout` and `interval` event
* types. These don't set up real event listeners, but instead invoke the
* action on a timer.
*
* @typedef {Object} PageEventListener
* @property {Function} callback Function to call when event is triggered
* @property {AbortController} controller Handle for aborting the listener
*
* @typedef {Object} PageEvent
* @property {String} type Event type string e.g. `click`
* @property {Element} [target] Event target
*/
/**
* Maps event listener params to their PageEventListeners, so they can be
* called and cancelled.
* @type {Map<PageEventListenerParams, PageEventListener>}
*/
_listeners = new Map();
/**
* @param {Window} win Window containing the document to listen to
*/
constructor(win) {
this.win = win;
this.doc = win.document;
}
/**
* Adds a page event listener.
* @param {PageEventListenerParams} params
* @param {Function} callback Function to call when event is triggered
*/
on(params, callback) {
if (this._listeners.has(params)) {
return;
}
const { type, selectors, options = {} } = params;
const listener = { callback };
if (selectors) {
const controller = new AbortController();
const opt = {
capture: !!options.capture,
passive: !options.preventDefault,
signal: controller.signal,
};
const targets = this.doc.querySelectorAll(selectors);
for (const target of targets) {
target.addEventListener(type, callback, opt);
}
listener.controller = controller;
} else if (["timeout", "interval"].includes(type) && options.interval) {
let interval;
const abort = () => this.win.clearInterval(interval);
const onInterval = () => {
callback({ type, target: type });
if (type === "timeout") {
abort();
}
};
interval = this.win.setInterval(onInterval, options.interval);
listener.callback = onInterval;
listener.controller = { abort };
}
this._listeners.set(params, listener);
}
/**
* Removes a page event listener.
* @param {PageEventListenerParams} params
*/
off(params) {
const listener = this._listeners.get(params);
if (!listener) {
return;
}
listener.controller?.abort();
this._listeners.delete(params);
}
/**
* Adds a page event listener that is removed after the first event.
* @param {PageEventListenerParams} params
* @param {Function} callback Function to call when event is triggered
*/
once(params, callback) {
const wrappedCallback = (...args) => {
this.off(params);
callback(...args);
};
this.on(params, wrappedCallback);
}
/**
* Removes all page event listeners.
*/
clear() {
for (const listener of this._listeners.values()) {
listener.controller?.abort();
}
this._listeners.clear();
}
/**
* Calls matching page event listeners. A way to dispatch a "fake" event.
* @param {PageEvent} event
*/
emit(event) {
for (const [params, listener] of this._listeners) {
if (params.type === event.type) {
listener.callback(event);
}
}
}
}