feat: add generic ProgressType parameter to Job and Worker

docs/gitbook/guide/workers/README.md

@@ -133,6 +133,33 @@ It is also possible to specify the data types for the Job data and return value
 const worker = new Worker<MyData, MyReturn>(queueName, async (job: Job) => {});
 ```
 
+By default the job progress is typed as `string | boolean | number | object`. If you report progress with a specific shape, you can also specify a progress type so that `updateProgress` and the `progress` event are type-safe:
+
+```typescript
+import { Worker, RedisQueueBackend } from 'bullmq';
+
+type MyProgress = { percentage: number; message: string };
+
+const worker = new Worker<
+  MyData,
+  MyReturn,
+  string,
+  RedisQueueBackend,
+  MyProgress
+>(queueName, async job => {
+  // progress is checked against MyProgress
+  await job.updateProgress({ percentage: 42, message: 'halfway' });
+});
+
+worker.on('progress', (job, progress) => {
+  console.log(progress.percentage, progress.message);
+});
+```
+
+{% hint style="info" %}
+The progress type must be JSON-serializable, as progress is persisted in the queue's backend. Sandboxed processors always receive the default progress type, since the value crosses a process boundary.
+{% endhint %}
+
 ## Read more:
 
 - 💡 [Worker API Reference](https://docs.bullmq.io/api/classes/v6.Worker.html)

src/classes/job.ts

@@ -55,7 +55,8 @@ export class Job<
   DataType = any,
   ReturnType = any,
   NameType extends string = string,
-> implements MinimalJob<DataType, ReturnType, NameType> {
+  ProgressType extends JobProgress = JobProgress,
+> implements MinimalJob<DataType, ReturnType, NameType, ProgressType> {
   /**
    * It includes the prefix, the namespace separator :, and queue name.
    * @see {@link https://www.gnu.org/software/gawk/manual/html_node/Qualified-Names.html}
@@ -66,7 +67,7 @@ export class Job<
    * The progress a job has performed so far.
    * @defaultValue 0
    */
-  progress: JobProgress = 0;
+  progress: ProgressType = 0 as ProgressType;
 
   /**
    * The value returned by the processor when processing this job.
@@ -539,7 +540,7 @@ export class Job<
    *
    * @param progress - number or object to be saved as progress.
    */
-  async updateProgress(progress: JobProgress): Promise<void> {
+  async updateProgress(progress: ProgressType): Promise<void> {
     this.progress = progress;
     await this.backend.updateProgress(this.id, progress);
     this.queue.emit('progress', this, progress);