Default Values in Collector

lib/collector.js

@@ -7,15 +7,17 @@ class Collector {
   count = 0;
   exact = true;
   timeout = 0;
+  defaultValue = {};
   #fulfill = null;
   #reject = null;
   #timer = null;
   #cause = null;
 
-  constructor(keys, { exact = true, timeout = 0 } = {}) {
+  constructor(keys, { exact = true, defaultValue = {}, timeout = 0 } = {}) {
     this.keys = keys;
     if (exact === false) this.exact = false;
     if (typeof timeout === 'number') this.#timeout(timeout);
+    if (typeof defaultValue === 'object') this.defaultValue = defaultValue;
   }
 
   #timeout(msec) {
@@ -25,7 +27,13 @@ class Collector {
       this.#timer = null;
     }
     if (msec === 0) return;
-    const handler = () => this.fail(new Error('Collector timed out'));
+    const handler = () => {
+      if (Object.keys(this.defaultValue).length)
+        for (const [key, value] of Object.entries(this.defaultValue)) {
+          this.set(key, value);
+        }
+      else this.fail(new Error('Collector timed out'));
+    };
     this.#timer = setTimeout(handler, msec);
   }
 

metautil.d.ts

@@ -234,6 +234,7 @@ export function sizeToBytes(size: string): number;
 
 export interface CollectorOptions {
   exact?: boolean;
+  defaultValue?: object;
   timeout?: number;
 }
 
@@ -246,6 +247,7 @@ export class Collector {
   count: number;
   exact: boolean;
   timeout: number;
+  defaultValue: object;
   constructor(keys: Array<string>, options?: CollectorOptions);
   set(key: string, value: unknown): void;
   wait(key: string, fn: AsyncFunction, ...args: Array<unknown>): void;

test/collector.js

@@ -97,6 +97,27 @@ metatests.test('Collector: timeout', async (test) => {
   }
 });
 
+metatests.test('Collector: defaultValue', async (test) => {
+  const defaultValue = { key1: 1 };
+
+  const dc1 = collect(['key1'], { defaultValue, timeout: 50 });
+  const dc2 = collect(['key1'], { defaultValue: {}, timeout: 50 });
+
+  setTimeout(() => {
+    dc1.set('key1', 2);
+    dc2.set('key1', 2);
+  }, 100);
+
+  try {
+    const result = await dc1;
+    test.strictSame(result, defaultValue);
+    await dc2;
+  } catch (error) {
+    test.strictSame(error.message, 'Collector timed out');
+  }
+  test.end();
+});
+
 metatests.test('Collector: fail', async (test) => {
   const dc = collect(['key1']);