HelloCities

Hello Cities — Durable Functions JavaScript Quickstart

JavaScript | Durable Functions

Description

This quickstart demonstrates Durable Functions with JavaScript (Node.js v4 programming model) using the Durable Task Scheduler backend. It includes two patterns:

1. Function Chaining — An orchestration that calls three "say hello" activities sequentially
2. Fan-out/Fan-in — An orchestration that greets multiple cities in parallel and aggregates results

Prerequisites

1. Node.js 18+
2. Azure Functions Core Tools v4
3. Docker (for the emulator)

Quick Run

1. Start the emulator:

   docker run -d -p 8080:8080 -p 8082:8082 mcr.microsoft.com/dts/dts-emulator:latest

2. Install dependencies and run:

   cd samples/durable-functions/javascript/HelloCities
   npm install
   func start

3. Trigger the function chaining orchestration:

   curl -X POST http://localhost:7071/api/StartChaining

4. Trigger the fan-out/fan-in orchestration:

   curl -X POST http://localhost:7071/api/StartFanOutFanIn

5. View in the dashboard: http://localhost:8082

Expected Output

The chaining orchestration greets Tokyo, Seattle, and London sequentially:

["Hello Tokyo!", "Hello Seattle!", "Hello London!"]

The fan-out/fan-in orchestration greets all five cities in parallel and returns combined results.

Learn More

• Durable Functions JavaScript API Reference
• Durable Functions JavaScript Quickstart
• Durable Task Scheduler Documentation