Quickstart: Use JavaScript to create a chat room with Azure Functions and SignalR Service

Azure SignalR Service lets you easily add real-time functionality to your application and Azure Functions is a serverless platform that lets you run your code without managing any infrastructure. In this quickstart, you use JavaScript to build a serverless, real-time chat application using SignalR Service and Functions.



This quickstart can be run on macOS, Windows, or Linux.

Having issues? Try the troubleshooting guide or let us know.

Log in to Azure

Sign in to the Azure portal at https://portal.azure.com/ with your Azure account.

Having issues? Try the troubleshooting guide or let us know.

Create an Azure SignalR Service instance

Your application will connect to a SignalR Service instance in Azure.

  1. Select the New button found on the upper left-hand corner of the Azure portal. In the New screen, type SignalR Service in the search box and press enter.

    Screenshot shows search for SignalR Service in the Azure portal.

  2. Select SignalR Service from the search results, then select Create.

  3. Enter the following settings.

    Setting Suggested value Description
    Resource name Globally unique name Name that identifies your new SignalR Service instance. Valid characters are a-z, 0-9, and -.
    Subscription Your subscription The subscription under which this new SignalR Service instance is created.
    Resource Group myResourceGroup Name for the new resource group in which to create your SignalR Service instance.
    Location West US Choose a region near you.
    Pricing tier Free Try Azure SignalR Service for free.
    Unit count Not applicable Unit count specifies how many connections your SignalR Service instance can accept. It is only configurable in the Standard tier.
    Service mode Serverless For use with Azure Functions or REST API.

    Screenshot shows SignalR Basics tab with values.

  4. Select Create to start deploying the SignalR Service instance.

  5. After the instance is deployed, open it in the portal and locate its Settings page. Change the Service Mode setting to Serverless only if you are using Azure SignalR Service through Azure Functions binding or REST API. Leave it in Classic or Default otherwise.

Having issues? Try the troubleshooting guide or let us know.

Clone the sample application

While the service is deploying, let's switch to working with code. Clone the sample app from GitHub, set the SignalR Service connection string, and run the application locally.

  1. Open a git terminal window. Change to a folder where you want to clone the sample project.

  2. Run the following command to clone the sample repository. This command creates a copy of the sample app on your computer.

    git clone https://github.com/Azure-Samples/signalr-service-quickstart-serverless-chat.git

Having issues? Try the troubleshooting guide or let us know.

Configure and run the Azure Function app

  1. In the browser where the Azure portal is opened, confirm the SignalR Service instance you deployed earlier was successfully created by searching for its name in the search box at the top of the portal. Select the instance to open it.

    Search for the SignalR Service instance

  2. Select Keys to view the connection strings for the SignalR Service instance.

  3. Select and copy the primary connection string.

    Screenshot that highlights the primary connection string.

  4. In your code editor, open the src/chat/javascript folder in the cloned repository.

  5. Rename local.settings.sample.json to local.settings.json.

  6. In local.settings.json, paste the connection string into the value of the AzureSignalRConnectionString setting. Save the file.

  7. JavaScript functions are organized into folders. In each folder are two files: function.json defines the bindings that are used in the function, and index.js is the body of the function. There are two HTTP triggered functions in this function app:

    • negotiate - Uses the SignalRConnectionInfo input binding to generate and return valid connection information.
    • messages - Receives a chat message in the request body and uses the SignalR output binding to broadcast the message to all connected client applications.
  8. In the terminal, ensure that you are in the src/chat/javascript folder. Run the function app.

    func start

    Create SignalR Service

Having issues? Try the troubleshooting guide or let us know.

Run the web application

  1. To simplify your client testing, open your browser to our sample single page web application https://azure-samples.github.io/signalr-service-quickstart-serverless-chat/demo/chat-v2/.


    The source of the HTML file is located at /docs/demo/chat-v2/index.html. And if you'd like to host the HTML yourself, please start a local HTTP server such as http-server in the /docs/demo/chat-v2 directory. Ensure the origin is added to the CORS setting in local.settings.json similar to the sample.

    "Host": {
     "LocalHttpPort": 7071,
     "CORS": "http://localhost:8080,https://azure-samples.github.io",
     "CORSCredentials": true
  2. When prompted for the function app base URL, enter http://localhost:7071.

  3. Enter a username when prompted.

  4. The web application calls the GetSignalRInfo function in the function app to retrieve the connection information to connect to Azure SignalR Service. When the connection is complete, the chat message input box appears.

  5. Type a message and press enter. The application sends the message to the SendMessage function in the Azure Function app, which then uses the SignalR output binding to broadcast the message to all connected clients. If everything is working correctly, the message should appear in the application.

    Run the application

  6. Open another instance of the web application in a different browser window. You will see that any messages sent will appear in all instances of the application.

Having issues? Try the troubleshooting guide or let us know.

Clean up resources

If you're not going to continue to use this app, delete all resources created by this quickstart with the following steps so you don't incur any charges:

  1. In the Azure portal, select Resource groups on the far left, and then select the resource group you created. Alternatively, you may use the search box to find the resource group by its name.

  2. In the window that opens, select the resource group, and then click Delete resource group.

  3. In the new window, type the name of the resource group to delete, and then click Delete.

Having issues? Try the troubleshooting guide or let us know.

Next steps

In this quickstart, you built and ran a real-time serverless application in VS Code. Next, learn more about how to deploy Azure Functions from VS Code.