Quickstart | Resonate TypeScript SDK

The function you are about to activate

A countdown as a loop. Simple, but the function can run for minutes, hours, or days, despite restarts.

import { Resonate, type Context } from "@resonatehq/sdk";

function* countdown(context: Context, count: number, delay: number) {
  for (let i = count; i > 0; i--) {
    // Run a function, persist its result
    yield* context.run((context: Context) => console.log(`Countdown: ${i}`));
    // Sleep
    yield* context.sleep(delay * 1000);
  }
  console.log("Done!");
}
// Instantiate Resonate
const resonate = new Resonate({ url: "http://localhost:8001" });
// Register the function
resonate.register(countdown);

Steps to run

1. Install the Resonate Server & CLI

brew install resonatehq/tap/resonate

2. Install the Resonate SDK

npm install @resonatehq/sdk

3. Start the server

resonate dev

4. Start the worker

npx ts-node countdown.ts

5. Run the function

Run the function with execution ID countdown.1:

resonate invoke countdown.1 --func countdown --arg 5 --arg 60

Result

You will see the countdown in the terminal

npx ts-node countdown.ts
Countdown: 5
Countdown: 4
Countdown: 3
Countdown: 2
Countdown: 1
Done!

What to try

After starting the function, inspect the current state of the execution using the resonate tree command. The tree command visualizes the call graph of the function execution as a graph of durable promises.

resonate tree countdown.1

Now try killing the worker mid-countdown and restarting. The countdown picks up right where it left off without missing a beat.

Next steps

• Learn how Resonate works
• Explore examples
• Build a real application