<pre class="shiki github-dark shaku"><code>// 1. recursionconst fetchListWithAmount = async (amount = 5) =&gt; { const result = []; let cursor = undefined; const call = async () =&gt; { const { items } = await fetchList(cursor); if (!items.length || !amount) return result; const min = Math.min(items.length, amount); result.push(...items.slice(0, min)); cursor = items.at(-1).id; amount -= min; return call(); }; return call();};// 2. generatorconst fetchListWithAmount = async (amount = 5) =&gt; { async function* fetchListGenerator() { let cursor = undefined; while (amount &gt; 0) { const { items } = await fetchList(cursor); if (!items.length) break; const min = Math.min(items.length, amount); cursor = items.at(-1).id; amount -= min; yield items.slice(0, min); } } let result = []; for await (const nextItems of fetchListGenerator()) { result = result.concat(nextItems); } return result;};// 3. async iteratorconst fetchListWithAmount = async (amount = 5) =&gt; { function fetchListIterator() { let cursor = undefined; return { [Symbol.asyncIterator]() { return { async next() { const { items } = await fetchList(cursor); if (!items.length || amount === 0) { return { done: true }; } const min = Math.min(items.length, amount); cursor = items.at(-1).id; amount -= min; return { done: false, value: items.slice(0, min), }; }, }; }, }; } let result = []; for await (const nextItems of fetchListIterator()) { result = result.concat(nextItems); } return result;};</code></pre>

JS - Recursion + Generator + Async Iterator

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,…