Default Values in Collector

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## [Unreleased][unreleased]
 
+- Added `defaults` to `Collector` options
+
 ## [5.1.0][] - 2023-12-17
 
 - Support waiting for promise in `Collector.wait`

lib/collector.js

@@ -8,29 +8,40 @@ class Collector {
   exact = true;
   reassign = true;
   timeout = 0;
+  defaults = {};
   #fulfill = null;
   #reject = null;
   #cause = null;
   #controller = null;
   #signal = null;
   #timeout = null;
 
-  constructor(keys, { exact = true, timeout = 0, reassign = false } = {}) {
+  constructor(keys, options = {}) {
+    const { exact = true, reassign = false } = options;
+    const { timeout = 0, defaults = {} } = options;
     this.keys = keys;
     if (exact === false) this.exact = false;
     if (reassign === false) this.reassign = reassign;
+    if (typeof defaults === 'object') this.defaults = defaults;
     this.#controller = new AbortController();
     this.#signal = this.#controller.signal;
     if (typeof timeout === 'number' && timeout > 0) {
       this.#timeout = AbortSignal.timeout(timeout);
       this.#signal = AbortSignal.any([this.#signal, this.#timeout]);
       this.#timeout.addEventListener('abort', () => {
+        if (Object.keys(this.defaults).length > 0) this.#default();
         if (this.done) return;
         this.fail(this.#timeout.reason);
       });
     }
   }
 
+  #default() {
+    for (const [key, value] of Object.entries(this.defaults)) {
+      if (this.data[key] === undefined) this.set(key, value);
+    }
+  }
+
   get signal() {
     return this.#controller.signal;
   }

metautil.d.ts

@@ -234,6 +234,7 @@ export function sizeToBytes(size: string): number;
 
 export interface CollectorOptions {
   exact?: boolean;
+  defaults?: object;
   timeout?: number;
   reassign?: boolean;
 }
@@ -247,6 +248,7 @@ export class Collector {
   count: number;
   exact: boolean;
   timeout: number;
+  defaults: object;
   reassign: boolean;
   signal: AbortSignal;
   constructor(keys: Array<string>, options?: CollectorOptions);

test/collector.js

@@ -100,6 +100,34 @@ metatests.test('Collector: timeout', async (test) => {
   }
 });
 
+metatests.test('Collector: default values', async (test) => {
+  const defaults = { key1: 1 };
+
+  const dc1 = collect(['key1'], { defaults, timeout: 50 });
+  const dc2 = collect(['key1'], { defaults: {}, timeout: 50 });
+  const dc3 = collect(['key1', 'key2'], { defaults, timeout: 50 });
+  dc3.set('key2', 1);
+
+  setTimeout(() => {
+    dc1.set('key1', 2);
+    dc2.set('key1', 2);
+    dc3.set('key1', 2);
+  }, 100);
+
+  const result1 = await dc1;
+  test.strictSame(result1, defaults);
+  const result3 = await dc3;
+  test.strictSame(result3, { ...defaults, key2: 1 });
+
+  try {
+    await dc2;
+    test.error(new Error('Should not be executed'));
+  } catch (error) {
+    test.strictSame(error.message, 'The operation was aborted due to timeout');
+  }
+  test.end();
+});
+
 metatests.test('Collector: fail', async (test) => {
   const dc = collect(['key1']);