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                button#start Start
button#stop Stop/Abort





                // Unsupported browser
if (!('AbortController' in window)) {
	document.getElementById('log').textContent = 'Your browser does not support AbortController. Please use Firefox or Edge for the time being.'

// Browser with support
else {
	// Example Promise, which takes signal into account
	function doSomethingAsync({signal}) {
		if (signal.aborted) {
			return Promise.reject(new DOMException('Aborted', 'AbortError'));

		return new Promise((resolve, reject) => {
			document.getElementById('log').textContent = 'Promise Started';

			// Something fake async
			const timeout = window.setTimeout(resolve, 2500, 'Promise Resolved')

			// Listen for abort event on signal
			signal.addEventListener('abort', () => {
				reject(new DOMException('Aborted', 'AbortError'));

	// Creation of an AbortController signal
	const controller = new AbortController();
	const signal = controller.signal;

	// Start our promise, catching errors (including abort)
	const start = (e) => {
		doSomethingAsync({ signal })
			.then(result => {
				document.getElementById('log').textContent = result;
			.catch(err => {
				if ( === 'AbortError') {
					document.getElementById('log').textContent = 'Promise Aborted';
				} else {
					document.getElementById('log').textContent = 'Promise Rejected';

	// Stop the promise (by calling abort)
	const stop = (e) => {

	// Hook events to buttons
	document.getElementById('start').addEventListener('click', start);
	document.getElementById('stop').addEventListener('click', stop);