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Diffstat (limited to '')
-rw-r--r-- | remote/shared/listeners/LoadListener.sys.mjs | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/remote/shared/listeners/LoadListener.sys.mjs b/remote/shared/listeners/LoadListener.sys.mjs new file mode 100644 index 0000000000..cccfca7a90 --- /dev/null +++ b/remote/shared/listeners/LoadListener.sys.mjs @@ -0,0 +1,103 @@ +/* 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 }); + } + }; +} |