mirror of
https://github.com/idanoo/GoScrobble.git
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97 lines
2.9 KiB
JavaScript
97 lines
2.9 KiB
JavaScript
/**
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* @callback EventCallback
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* @param {string | Error | null} context
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* @returns {void}
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*/
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/**
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* @callback EventHandler
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* @param {Event} event
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* @returns {void}
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*/
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/**
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* A function that creates an event handler for the `error` event.
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* @param {EventCallback} callback A function called to handle the error context.
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* @returns {EventHandler} A handler for the `error` event.
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*/
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function createErrorHandler(callback) {
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return function errorHandler(event) {
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if (!event || !event.error) {
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return callback(null);
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}
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if (event.error instanceof Error) {
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return callback(event.error);
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}
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// A non-error was thrown, we don't have a trace. :(
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// Look in your browser's devtools for more information
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return callback(new Error(event.error));
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};
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}
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/**
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* A function that creates an event handler for the `unhandledrejection` event.
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* @param {EventCallback} callback A function called to handle the error context.
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* @returns {EventHandler} A handler for the `unhandledrejection` event.
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*/
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function createRejectionHandler(callback) {
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return function rejectionHandler(event) {
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if (!event || !event.reason) {
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return callback(new Error('Unknown'));
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}
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if (event.reason instanceof Error) {
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return callback(event.reason);
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}
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// A non-error was rejected, we don't have a trace :(
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// Look in your browser's devtools for more information
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return callback(new Error(event.reason));
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};
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}
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/**
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* Creates a handler that registers an EventListener on window for a valid type
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* and calls a callback when the event fires.
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* @param {string} eventType A valid DOM event type.
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* @param {function(EventCallback): EventHandler} createHandler A function that creates an event handler.
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* @returns {register} A function that registers the EventListener given a callback.
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*/
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function createWindowEventHandler(eventType, createHandler) {
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/**
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* @type {EventHandler | null} A cached event handler function.
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*/
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let eventHandler = null;
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/**
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* Unregisters an EventListener if it has been registered.
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* @returns {void}
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*/
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function unregister() {
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if (eventHandler === null) {
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return;
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}
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window.removeEventListener(eventType, eventHandler);
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eventHandler = null;
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}
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/**
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* Registers an EventListener if it hasn't been registered.
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* @param {EventCallback} callback A function called after the event handler to handle its context.
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* @returns {unregister | void} A function to unregister the registered EventListener if registration is performed.
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*/
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function register(callback) {
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if (eventHandler !== null) {
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return;
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}
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eventHandler = createHandler(callback);
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window.addEventListener(eventType, eventHandler);
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return unregister;
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}
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return register;
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}
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module.exports = {
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error: createWindowEventHandler('error', createErrorHandler),
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unhandledRejection: createWindowEventHandler('unhandledrejection', createRejectionHandler),
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};
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