148. Abortable Fetch Wrapper

Implement an abortableFetch wrapper that adds strict timeout and cancellation bounds to the standard fetch protocol.

The native fetch API does not time out by default. In production environments, leaving network requests unbounded causes memory leaks, paralyzes UI states, and exhausts connection pools. Senior engineers always set upper bounds on async IO.

Implement

function abortableFetch(url, options, fetchFn) {}

• Timeout Control: If the timeoutMs ceiling is reached, the Promise must reject immediately with new Error('TimeoutError').
• Connection Teardown: Upon a timeout, you must explicitly abort the underlying network connection using AbortController to free up the socket/browser connection pool.
• Synchronous Validation: You must validate that fetchFn is a function before initiating timers or promises.
• Signal Inheritance: If an AbortSignal is provided in the options, it must be correctly linked to the fetch request.

Examples

// Example: Resolves normally if fetch finishes in time
await abortableFetch('/api/data', { timeoutMs: 5000 }, fetch);

// Example: Rejects with Error("TimeoutError") after 100ms
// The underlying socket is explicitly terminated
try {
  await abortableFetch('/api/slow', { timeoutMs: 100 }, fetch);
} catch (err) {
  console.error(err.message); // "TimeoutError"
}