Function rateLimited

rateLimited<ArgsType extends unknown[], T>(
fn: (...args: ArgsType) => Promise<T>,
duration_ms: number | (() => number),
): RateLimitedFunction<ArgsType, T>
Serializes async calls in FIFO order with a minimum delay between their start times.

Useful for throttling API calls without overlapping requests.
Type Parameters
- ArgsType extends unknown[]
  Tuple of the function's parameter types.
- T
  The resolved return type.
Parameters
- fn: (...args: ArgsType) => Promise<T>
  The async function to rate-limit.
- duration_ms: number | (() => number)
  Minimum delay (ms), or a function returning the delay dynamically.
Returns RateLimitedFunction<ArgsType, T>
A RateLimitedFunction.
Remarks
A call waits for both the previous call to settle and its start-to-start cooldown, including when the queue was empty between calls. The first call has no cooldown. Dynamic durations are sampled when scheduling queued work and again when a timer fires, not continuously; changing the duration does not wake an existing timer early. Timer precision and maximum supported delays are platform-dependent.
Example
```
const limitedFetch = rateLimited(fetchJson, 500);
await limitedFetch("/endpoint"); // executes immediately
await limitedFetch("/endpoint"); // starts ≥500ms after the previous start
```
- Defined in function/rate-limit.ts:54