Azure Functions Node.js 18: New Runtime Features

Azure Functions now supports Node.js 18, bringing modern JavaScript features and improved performance to serverless applications. This update enables developers to use the latest ECMAScript features and native fetch API.

Setting Up Node.js 18

Create a new Function App with Node.js 18:

# Install Azure Functions Core Tools
npm install -g azure-functions-core-tools@4

# Create new function project
func init my-functions --worker-runtime node --language typescript

# Update package.json engine
cd my-functions

Update your configuration:

// package.json
{
  "name": "my-functions",
  "version": "1.0.0",
  "engines": {
    "node": ">=18.0.0"
  },
  "main": "dist/src/functions/*.js",
  "scripts": {
    "build": "tsc",
    "watch": "tsc -w",
    "prestart": "npm run build",
    "start": "func start",
    "test": "jest"
  },
  "dependencies": {
    "@azure/functions": "^4.0.0"
  },
  "devDependencies": {
    "@types/node": "^18.0.0",
    "typescript": "^4.9.0"
  }
}

New Programming Model

Azure Functions v4 introduces a new programming model:

// src/functions/httpTrigger.ts
import {
  app,
  HttpRequest,
  HttpResponseInit,
  InvocationContext,
} from "@azure/functions";

export async function httpTrigger(
  request: HttpRequest,
  context: InvocationContext
): Promise<HttpResponseInit> {
  context.log(`Http function processed request for url "${request.url}"`);

  const name = request.query.get("name") || (await request.text()) || "World";

  return {
    status: 200,
    jsonBody: {
      message: `Hello, ${name}!`,
      timestamp: new Date().toISOString(),
    },
  };
}

app.http("httpTrigger", {
  methods: ["GET", "POST"],
  authLevel: "anonymous",
  handler: httpTrigger,
});

Native Fetch API

Use the built-in fetch without external dependencies:

// src/functions/fetchData.ts
import {
  app,
  HttpRequest,
  HttpResponseInit,
  InvocationContext,
} from "@azure/functions";

interface GitHubUser {
  login: string;
  name: string;
  public_repos: number;
  followers: number;
}

export async function fetchGitHubUser(
  request: HttpRequest,
  context: InvocationContext
): Promise<HttpResponseInit> {
  const username = request.query.get("username");

  if (!username) {
    return {
      status: 400,
      jsonBody: { error: "Username is required" },
    };
  }

  try {
    // Native fetch - no dependencies needed!
    const response = await fetch(`https://api.github.com/users/${username}`, {
      headers: {
        Accept: "application/vnd.github.v3+json",
        "User-Agent": "Azure-Functions",
      },
    });

    if (!response.ok) {
      if (response.status === 404) {
        return {
          status: 404,
          jsonBody: { error: "User not found" },
        };
      }
      throw new Error(`GitHub API error: ${response.status}`);
    }

    const user: GitHubUser = await response.json();

    return {
      status: 200,
      jsonBody: {
        login: user.login,
        name: user.name,
        publicRepos: user.public_repos,
        followers: user.followers,
      },
    };
  } catch (error) {
    context.error("Failed to fetch GitHub user", error);
    return {
      status: 500,
      jsonBody: { error: "Failed to fetch user data" },
    };
  }
}

app.http("fetchGitHubUser", {
  methods: ["GET"],
  authLevel: "anonymous",
  route: "github/user",
  handler: fetchGitHubUser,
});

Timer Trigger with Async Operations

// src/functions/scheduledCleanup.ts
import { app, InvocationContext, Timer } from "@azure/functions";
import { BlobServiceClient } from "@azure/storage-blob";

const connectionString = process.env.STORAGE_CONNECTION_STRING!;
const blobServiceClient =
  BlobServiceClient.fromConnectionString(connectionString);

export async function scheduledCleanup(
  myTimer: Timer,
  context: InvocationContext
): Promise<void> {
  context.log("Cleanup function started", myTimer);

  const containerClient = blobServiceClient.getContainerClient("temp-files");
  const cutoffDate = new Date();
  cutoffDate.setDate(cutoffDate.getDate() - 7); // 7 days ago

  let deletedCount = 0;

  // Use async iterator for blobs
  for await (const blob of containerClient.listBlobsFlat()) {
    if (blob.properties.lastModified && blob.properties.lastModified < cutoffDate) {
      const blobClient = containerClient.getBlobClient(blob.name);
      await blobClient.delete();
      deletedCount++;
      context.log(`Deleted blob: ${blob.name}`);
    }
  }

  context.log(`Cleanup completed. Deleted ${deletedCount} blobs.`);
}

app.timer("scheduledCleanup", {
  schedule: "0 0 2 * * *", // Run at 2 AM daily
  handler: scheduledCleanup,
});

Queue Trigger with Batching

// src/functions/processOrders.ts
import { app, InvocationContext } from "@azure/functions";

interface Order {
  id: string;
  customerId: string;
  items: { productId: string; quantity: number }[];
  totalAmount: number;
}

export async function processOrders(
  messages: Order[],
  context: InvocationContext
): Promise<void> {
  context.log(`Processing batch of ${messages.length} orders`);

  // Process orders concurrently
  const results = await Promise.allSettled(
    messages.map(async (order) => {
      context.log(`Processing order ${order.id}`);

      // Validate order
      if (!order.items || order.items.length === 0) {
        throw new Error(`Order ${order.id} has no items`);
      }

      // Process each item
      for (const item of order.items) {
        await processOrderItem(order.id, item, context);
      }

      // Notify customer
      await sendConfirmationEmail(order, context);

      return order.id;
    })
  );

  // Log results
  const successful = results.filter((r) => r.status === "fulfilled");
  const failed = results.filter((r) => r.status === "rejected");

  context.log(`Batch complete: ${successful.length} succeeded, ${failed.length} failed`);

  if (failed.length > 0) {
    const errors = failed.map((r) =>
      r.status === "rejected" ? r.reason : "unknown"
    );
    context.error("Failed orders:", errors);
  }
}

async function processOrderItem(
  orderId: string,
  item: { productId: string; quantity: number },
  context: InvocationContext
): Promise<void> {
  // Call inventory service using native fetch
  const response = await fetch(process.env.INVENTORY_SERVICE_URL!, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({
      orderId,
      productId: item.productId,
      quantity: item.quantity,
    }),
  });

  if (!response.ok) {
    throw new Error(`Inventory service error: ${response.status}`);
  }
}

async function sendConfirmationEmail(
  order: Order,
  context: InvocationContext
): Promise<void> {
  context.log(`Sending confirmation for order ${order.id}`);
  // Email logic here
}

app.storageQueue("processOrders", {
  queueName: "orders",
  connection: "STORAGE_CONNECTION_STRING",
  handler: processOrders,
});

Blob Trigger with Stream Processing

// src/functions/processImage.ts
import { app, InvocationContext } from "@azure/functions";
import { BlobServiceClient } from "@azure/storage-blob";

export async function processImage(
  blob: Buffer,
  context: InvocationContext
): Promise<void> {
  const blobName = context.triggerMetadata.name as string;
  context.log(`Processing image: ${blobName}, size: ${blob.length} bytes`);

  // Process the image (resize, convert, etc.)
  const processedImage = await transformImage(blob);

  // Upload to processed container
  const blobServiceClient = BlobServiceClient.fromConnectionString(
    process.env.STORAGE_CONNECTION_STRING!
  );
  const containerClient = blobServiceClient.getContainerClient("processed-images");
  const outputBlobClient = containerClient.getBlockBlobClient(
    `processed-${blobName}`
  );

  await outputBlobClient.upload(processedImage, processedImage.length, {
    blobHTTPHeaders: {
      blobContentType: "image/webp",
    },
  });

  context.log(`Processed image uploaded: processed-${blobName}`);
}

async function transformImage(buffer: Buffer): Promise<Buffer> {
  // Image processing logic here
  // In production, use sharp or similar library
  return buffer;
}

app.storageBlob("processImage", {
  path: "uploads/{name}",
  connection: "STORAGE_CONNECTION_STRING",
  handler: processImage,
});

Cosmos DB Trigger

// src/functions/cosmosDBTrigger.ts
import { app, InvocationContext } from "@azure/functions";

interface Document {
  id: string;
  type: string;
  data: any;
  _ts: number;
}

export async function cosmosDBTrigger(
  documents: Document[],
  context: InvocationContext
): Promise<void> {
  context.log(`Cosmos DB trigger received ${documents.length} documents`);

  for (const doc of documents) {
    context.log(`Document id: ${doc.id}, type: ${doc.type}`);

    switch (doc.type) {
      case "order":
        await handleOrderChange(doc, context);
        break;
      case "customer":
        await handleCustomerChange(doc, context);
        break;
      default:
        context.log(`Unknown document type: ${doc.type}`);
    }
  }
}

async function handleOrderChange(
  doc: Document,
  context: InvocationContext
): Promise<void> {
  // Sync to search index, send notifications, etc.
  context.log(`Processing order change: ${doc.id}`);
}

async function handleCustomerChange(
  doc: Document,
  context: InvocationContext
): Promise<void> {
  // Update related records, trigger workflows, etc.
  context.log(`Processing customer change: ${doc.id}`);
}

app.cosmosDB("cosmosDBTrigger", {
  connectionStringSetting: "COSMOS_CONNECTION_STRING",
  databaseName: "ecommerce",
  collectionName: "items",
  createLeaseCollectionIfNotExists: true,
  handler: cosmosDBTrigger,
});

Summary

Node.js 18 in Azure Functions brings:

• New v4 programming model with cleaner syntax
• Native fetch API for HTTP requests
• Improved TypeScript support
• Better async/await patterns
• Enhanced performance and memory management

This update makes Azure Functions more aligned with modern Node.js development practices.

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References:

• Azure Functions Node.js Developer Guide
• Azure Functions v4 Programming Model
• Node.js 18 Release Notes