nobl

Nobl lets you write long-running loops that run asynchronously instead of blocking the thread, by automatically ceding control back to the browser at regular intervals (every 20ms).

• Non-blocking loops
• "knobble" / "noble" / "no bull"

Usage

Put await nobl() wherever you want the code to potentially cede control to the browser. It doesn't necessarily cede control every time. Only once every 20ms.

import { nobl } from 'nobl';

async function longOperation() {
  for (let i = 0; i < hugeNumber; i++) {
    if (someCondition(i)) {
      smallPieceOfTheOperation(i);
    }
    await nobl(); // inside the loop, outside the `if` block
  }
}

Options

nobl() accepts as an optional argument an object with two optional properties:

Option | Type -----------|---------- cancel | boolean progress | function

cancel

If the cancel option is truthy, a NoblCancelled error is thrown.

let cancel = false;
async function longOperation() {
  for (let i = 0; i < hugeNumber; i++) {
    // ...
    await nobl({cancel});
  }
}

setTimeout(() => {
  cancel = true;
}, 1000);

try {
  await longOperation();
} catch (e) {
  if (e instanceof NoblCancelled) {
    // ...
  }
}

progress

If the progress option is a function, it runs once every time control is ceded.

import { nobl } from 'nobl';

function progress() {
  // Update a progress bar or something
}

async function longOperation() {
  for (let i = 0; i < hugeNumber; i++) {
    if (someCondition(i)) {
      smallPieceOfTheOperation(i);
    }
    await nobl({progress});
  }
}

Caveat

Nobl is experimental and hasn't seen much real-world use. You probably shouldn't rely on it for mission-critical applications.

License

MIT