oauth.js

await (async () => {
	const formUrlEncode = params => Object.entries(params).map(([k, v]) => `${encodeURIComponent(k)}=${encodeURIComponent(v)}`).join(`&`)
	const auth = `Bearer ` + await fetch(`https://www.example.com/api/oauth2`, {
		method: 'POST',
		headers: {
			'Content-Type': 'application/x-www-form-urlencoded',
		},
		body: formUrlEncode({
			username: 'admin',
			password: '1234',
		}),
		credentials: 'omit',
		referrerPolicy: 'no-referrer',
	}).then(r => r.json()).then(r => r.access_token);
	const beans = await fetch(`https://www.example.com/api/cool-beans`, {
		headers: {
			Authorization: auth,
		},
		credentials: 'omit',
		referrerPolicy: 'no-referrer',
	}).then(r => r.json()).then(r => r.beans);
	return beans;
})();