index.cjs

'use strict';

const objectToString = Object.prototype.toString;

const isError = value => objectToString.call(value) === '[object Error]';

const errorMessages = new Set([
	'network error', // Chrome
	'Failed to fetch', // Chrome
	'NetworkError when attempting to fetch resource.', // Firefox
	'The Internet connection appears to be offline.', // Safari 16
	'Load failed', // Safari 17+
	'Network request failed', // `cross-fetch`
	'fetch failed', // Undici (Node.js)
	'terminated', // Undici (Node.js)
]);

function isNetworkError(error) {
	const isValid = error
		&& isError(error)
		&& error.name === 'TypeError'
		&& typeof error.message === 'string';

	if (!isValid) {
		return false;
	}

	// We do an extra check for Safari 17+ as it has a very generic error message.
	// Network errors in Safari have no stack.
	if (error.message === 'Load failed') {
		return error.stack === undefined;
	}

	return errorMessages.has(error.message);
}

module.exports = isNetworkError;