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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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
const lazy = {};
ChromeUtils.defineESModuleGetters(lazy, {
EventEmitter: "resource://gre/modules/EventEmitter.sys.mjs",
});
/**
* The LoadListener can be used to listen for load events.
*
* Example:
* ```
* const listener = new LoadListener();
* listener.on("DOMContentLoaded", onDOMContentLoaded);
* listener.startListening();
*
* const onDOMContentLoaded = (eventName, data = {}) => {
* const { target } = data;
* ...
* };
* ```
*
* @fires message
* The LoadListener emits "DOMContentLoaded" and "load" events,
* with the following object as payload:
* - {Document} target
* The target document.
*/
export class LoadListener {
#abortController;
#window;
/**
* Create a new LoadListener instance.
*/
constructor(win) {
lazy.EventEmitter.decorate(this);
// Use an abort controller instead of removeEventListener because destroy
// might be called close to the window global destruction.
this.#abortController = null;
this.#window = win;
}
destroy() {
this.stopListening();
}
startListening() {
if (this.#abortController) {
return;
}
this.#abortController = new AbortController();
// Events are attached to the windowRoot instead of the regular window to
// avoid issues with document.open (Bug 1822772).
this.#window.windowRoot.addEventListener(
"DOMContentLoaded",
this.#onDOMContentLoaded,
{
capture: true,
mozSystemGroup: true,
signal: this.#abortController.signal,
}
);
this.#window.windowRoot.addEventListener("load", this.#onLoad, {
capture: true,
mozSystemGroup: true,
signal: this.#abortController.signal,
});
}
stopListening() {
if (!this.#abortController) {
return;
}
this.#abortController.abort();
this.#abortController = null;
}
#onDOMContentLoaded = event => {
// Check that this event was emitted for the relevant window, because events
// from inner frames can bubble to the windowRoot.
if (event.target.defaultView === this.#window) {
this.emit("DOMContentLoaded", { target: event.target });
}
};
#onLoad = event => {
// Check that this event was emitted for the relevant window, because events
// from inner frames can bubble to the windowRoot.
if (event.target.defaultView === this.#window) {
this.emit("load", { target: event.target });
}
};
}
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