Improving mapping performance with web workers

We can use web workers to execute the computationally intensive mapping operation in a separate thread. This can be done by following these steps:

1. Create a new TS file for the worker
```
// worker.ts

// define the input and output types
type WorkerInput<T, U> = { data: T, mapFn: (x: T) => U };
type WorkerOutput<U> = { data: U[] };

// function for the actual work on the data
function doWork<T, U>(input: WorkerInput<T, U>): Promise<WorkerOutput<U>> {
  // Apply the mapping function to the input data.
  const mappedData = input.data.map(input.mapFn);

  // Return the mapped data as a promise.
  return Promise.resolve({ data: mappedData });
}
```

2. Use the worker in the main.ts file

```
// main.ts
const worker = new Worker('worker.ts');

// Define the mapping function.
const mapFn = (x: number) => x * x;

// Send data and the mapping function to the worker for processing.
worker.postMessage({ data: [1, 2, 3], mapFn });

// Listen for the message with the result from the worker
worker.addEventListener('message', (event) => {
    console.log(`Received message from worker: ${event.data}`)
});
```

Rares Raulea
09 Dec 2022