<pre class="shiki github-dark shaku"><code>// fetchList is provided for you// const fetchList = (since?: number) =&gt; // Promise&lt;{items: Array&lt;{id: number}&gt;}&gt;/** * Using async/await loop */async function fetchListWithAmount(amount = 5) { let cursor; const result = []; while (result.length &lt; amount) { const { items } = await fetchList(cursor); if (items.length &gt; 0) { result.push(...items); cursor = items[items.length - 1].id; } else { break; } } return result.slice(0, amount);}/** * Using async iterator */async function fetchListWithAmount(amount = 5) { const result = []; for await (const nextItems of fetchListIterator()) { result.push(...nextItems); } return result.slice(0, amount); function fetchListIterator() { let totalAmountFetched = 0; let cursor; return { [Symbol.asyncIterator]() { return { async next() { const { items } = await fetchList(cursor); // If API is exhausted OR we reached desired amount -&gt; stop if (items.length === 0 || totalAmountFetched &gt; amount) { return { done: true }; } totalAmountFetched += items.length; cursor = items[items.length - 1].id; return { done: false, value: items, } } }; }, }; }}/** * Using async generator */async function fetchListWithAmount(amount = 5) { const result = []; for await (const nextItems of fetchListGenerator()) { result.push(...nextItems); } return result.slice(0, amount); async function* fetchListGenerator() { let totalAmountFetched = 0; let cursor; while (totalAmountFetched &lt; amount) { const { items } = await fetchList(cursor); if (items.length === 0) break; cursor = items[items.length - 1].id; totalAmountFetched += items.length; yield items; } }}/** * Using recursion and Promise */function fetchListWithAmount(amount = 5) { return new Promise((resolve) =&gt; { const result = []; getItems(); function getItems(cursor) { fetchList(cursor).then(({ items }) =&gt; { result.push(...items); if (items.length === 0 || items.length &gt;= amount) { return resolve(result.slice(0, amount)); } getItems(items[items.length - 1].id); }); } });}</code></pre>

4 ways: Async/await loop, async iterator, async generator, recursion with regular promise

Have you ever met some APIs with pagination, and needed to recursively fetch them based on response of previous request ? Suppose we have a /list API,…