// an simple endpoint for getting current list let list = ['Item 1', 'Item 2', 'Item 3'] export default async (req, res) => { if (req.query.add) { if (!list.includes(req.query.add)) { list.push(req.query.add) } } else if (req.query.clear) { list = [] } await new Promise(r => setTimeout(r, 100)) res.json(list) }