Fetch interceptor

fetch-interceptor.js

let _fetch = window.fetch;

window.fetch = (url, options) => {
	return new Promise((resolve, reject) => {
		let p = _fetch(url, options);

		document.dispatchEvent(new CustomEvent('fetchStart', { detail: p }));

		p.then(response => {
			if (response.ok) {
				return response;
			} else {
				let error = new Error(response.statusText);

				error.response = response;

				throw error;
			}
		}).catch(error => {
			document.dispatchEvent(new CustomEvent('fetchError', { detail: error.response }));

			reject(error);
		}).then(response => {
			document.dispatchEvent(new CustomEvent('fetchEnd', { detail: response }));

			resolve(response);
		});
	});
};