Add property to get the queue size (#39)

index.d.ts

@@ -10,15 +10,20 @@ type PromiseResolve<ValueType> = ValueType extends PromiseLike<infer ValueType>
 export type ThrottledFunction<Argument extends readonly unknown[], ReturnValue> = ((...arguments: Argument) => PromiseResolve<ReturnValue>)
 & {
  /**
-  Whether future function calls should be throttled or count towards throttling thresholds.
+ Whether future function calls should be throttled or count towards throttling thresholds.
 
-  @default true
-  */
+ @default true
+ */
  isEnabled: boolean;
 
  /**
- Abort pending executions. All unresolved promises are rejected with a `pThrottle.AbortError` error.
- */
+ The number of queued items waiting to be executed.
+ */
+ readonly queueSize: number;
+
+ /**
+ Abort pending executions. All unresolved promises are rejected with a `pThrottle.AbortError` error.
+ */
  abort(): void;
 };
 

index.js

@@ -92,6 +92,12 @@ export default function pThrottle({limit, interval, strict}) {
 
  throttled.isEnabled = true;
 
+ Object.defineProperty(throttled, 'queueSize', {
+ get() {
+ return queue.size;
+ },
+ });
+
  return throttled;
  };
 }

index.test-d.ts

@@ -41,3 +41,4 @@ strictThrottledLazyUnicorn.abort();
 throttledTaggedUnicorn.abort();
 
 expectType<boolean>(throttledUnicorn.isEnabled);
+expectType<number>(throttledUnicorn.queueSize);

readme.md

@@ -96,6 +96,12 @@ Default: `true`
 
 Whether future function calls should be throttled and count towards throttling thresholds.
 
+### throttledFn.queueSize
+
+Type: `number`
+
+The number of queued items waiting to be executed.
+
 ## Related
 
 - [p-debounce](https://github.com/sindresorhus/p-debounce) - Debounce promise-returning & async functions

test.js

@@ -22,6 +22,25 @@ test('main', async t => {
  }));
 });
 
+test('queue size', async t => {
+ const limit = 10;
+ const interval = 100;
+ const throttled = pThrottle({limit, interval})(() => Date.now());
+ const promises = [];
+
+ t.is(throttled.queueSize, 0);
+
+ for (let index = 0; index < limit; index++) {
+ promises.push(throttled());
+ }
+
+ t.is(throttled.queueSize, limit);
+
+ await Promise.all(promises);
+
+ t.is(throttled.queueSize, 0);
+});
+
 test('strict mode', async t => {
  const totalRuns = 100;
  const limit = 5;