| 1 | /**
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| 2 | * @callback EventCallback
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| 3 | * @param {string | Error | null} context
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| 4 | * @returns {void}
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| 5 | */
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| 6 | /**
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| 7 | * @callback EventHandler
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| 8 | * @param {Event} event
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| 9 | * @returns {void}
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| 10 | */
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| 11 |
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| 12 | /**
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| 13 | * A function that creates an event handler for the `error` event.
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| 14 | * @param {EventCallback} callback A function called to handle the error context.
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| 15 | * @returns {EventHandler} A handler for the `error` event.
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| 16 | */
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| 17 | function createErrorHandler(callback) {
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| 18 | return function errorHandler(event) {
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| 19 | if (!event || !event.error) {
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| 20 | return callback(null);
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| 21 | }
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| 22 | if (event.error instanceof Error) {
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| 23 | return callback(event.error);
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| 24 | }
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| 25 | // A non-error was thrown, we don't have a trace. :(
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| 26 | // Look in your browser's devtools for more information
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| 27 | return callback(new Error(event.error));
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| 28 | };
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| 29 | }
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| 30 |
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| 31 | /**
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| 32 | * A function that creates an event handler for the `unhandledrejection` event.
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| 33 | * @param {EventCallback} callback A function called to handle the error context.
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| 34 | * @returns {EventHandler} A handler for the `unhandledrejection` event.
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| 35 | */
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| 36 | function createRejectionHandler(callback) {
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| 37 | return function rejectionHandler(event) {
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| 38 | if (!event || !event.reason) {
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| 39 | return callback(new Error('Unknown'));
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| 40 | }
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| 41 | if (event.reason instanceof Error) {
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| 42 | return callback(event.reason);
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| 43 | }
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| 44 | // A non-error was rejected, we don't have a trace :(
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| 45 | // Look in your browser's devtools for more information
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| 46 | return callback(new Error(event.reason));
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| 47 | };
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| 48 | }
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| 49 |
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| 50 | /**
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| 51 | * Creates a handler that registers an EventListener on window for a valid type
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| 52 | * and calls a callback when the event fires.
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| 53 | * @param {string} eventType A valid DOM event type.
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| 54 | * @param {function(EventCallback): EventHandler} createHandler A function that creates an event handler.
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| 55 | * @returns {register} A function that registers the EventListener given a callback.
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| 56 | */
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| 57 | function createWindowEventHandler(eventType, createHandler) {
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| 58 | /**
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| 59 | * @type {EventHandler | null} A cached event handler function.
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| 60 | */
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| 61 | let eventHandler = null;
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| 62 |
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| 63 | /**
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| 64 | * Unregisters an EventListener if it has been registered.
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| 65 | * @returns {void}
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| 66 | */
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| 67 | function unregister() {
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| 68 | if (eventHandler === null) {
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| 69 | return;
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| 70 | }
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| 71 | window.removeEventListener(eventType, eventHandler);
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| 72 | eventHandler = null;
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| 73 | }
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| 74 |
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| 75 | /**
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| 76 | * Registers an EventListener if it hasn't been registered.
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| 77 | * @param {EventCallback} callback A function called after the event handler to handle its context.
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| 78 | * @returns {unregister | void} A function to unregister the registered EventListener if registration is performed.
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| 79 | */
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| 80 | function register(callback) {
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| 81 | if (eventHandler !== null) {
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| 82 | return;
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| 83 | }
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| 84 | eventHandler = createHandler(callback);
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| 85 | window.addEventListener(eventType, eventHandler);
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| 86 |
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| 87 | return unregister;
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| 88 | }
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| 89 |
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| 90 | return register;
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| 91 | }
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| 92 |
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| 93 | const handleError = createWindowEventHandler('error', createErrorHandler);
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| 94 | const handleUnhandledRejection = createWindowEventHandler(
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| 95 | 'unhandledrejection',
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| 96 | createRejectionHandler
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| 97 | );
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| 98 |
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| 99 | module.exports = {
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| 100 | handleError: handleError,
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| 101 | handleUnhandledRejection: handleUnhandledRejection,
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| 102 | };
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