Quickstart: Create a JavaScript function in Azure from the command line

In this article, you use command-line tools to create a JavaScript function that responds to HTTP requests. After testing the code locally, you deploy it to the serverless environment of Azure Functions.

Completion of this quickstart incurs a small cost of a few USD cents or less in your Azure account.

There's also a Visual Studio Code-based version of this article.

Configure your local environment

Before you begin, you must have the following prerequisites:

• An Azure account with an active subscription. Create an account.

• One of the following tools for creating Azure resources:

  • Azure CLI version 2.4 or later.

  • The Azure Az PowerShell module version 5.9.0 or later.

Install the Azure Functions Core Tools

The recommended way to install Core Tools depends on the operating system of your local development computer.

Create a local function project

In Azure Functions, a function project is a container for one or more individual functions that each responds to a specific trigger. All functions in a project share the same local and hosting configurations. In this section, you create a function project that contains a single function.

module.exports = async function (context, req) {
    context.log('JavaScript HTTP trigger function processed a request.');

    const name = (req.query.name || (req.body && req.body.name));
    const responseMessage = name
        ? "Hello, " + name + ". This HTTP triggered function executed successfully."
        : "This HTTP triggered function executed successfully. Pass a name in the query string or in the request body for a personalized response.";

    context.res = {
        // status: 200, /* Defaults to 200 */
        body: responseMessage
    };
}

{
    "bindings": [
        {
            "authLevel": "function",
            "type": "httpTrigger",
            "direction": "in",
            "name": "req",
            "methods": [
                "get",
                "post"
            ]
        },
        {
            "type": "http",
            "direction": "out",
            "name": "res"
        }
    ]
}

Run the function locally

1. Run your function by starting the local Azure Functions runtime host from the LocalFunctionProj folder.

   func start
   

   Toward the end of the output, the following lines must appear:

   

   Note

   If HttpExample doesn't appear as shown above, you likely started the host from outside the root folder of the project. In that case, use Ctrl+C to stop the host, go to the project's root folder, and run the previous command again.

2. Copy the URL of your HTTP function from this output to a browser and append the query string ?name=<YOUR_NAME>, making the full URL like http://localhost:7071/api/HttpExample?name=Functions. The browser should display a response message that echoes back your query string value. The terminal in which you started your project also shows log output as you make requests.

3. When you're done, press Ctrl + C and type y to stop the functions host.

Create supporting Azure resources for your function

Before you can deploy your function code to Azure, you need to create three resources:

• A resource group, which is a logical container for related resources.
• A Storage account, which is used to maintain state and other information about your functions.
• A function app, which provides the environment for executing your function code. A function app maps to your local function project and lets you group functions as a logical unit for easier management, deployment, and sharing of resources.

Use the following commands to create these items. Both Azure CLI and PowerShell are supported.

1. If you haven't done so already, sign in to Azure:

   • Azure CLI
   • Azure PowerShell

   az login
   

   The az login command signs you into your Azure account.

2. Create a resource group named AzureFunctionsQuickstart-rg in your chosen region:

   • Azure CLI
   • Azure PowerShell

   az group create --name AzureFunctionsQuickstart-rg --location <REGION>
   

   The az group create command creates a resource group. In the above command, replace <REGION> with a region near you, using an available region code returned from the az account list-locations command.

3. Create a general-purpose storage account in your resource group and region:

   • Azure CLI
   • Azure PowerShell

   az storage account create --name <STORAGE_NAME> --location <REGION> --resource-group AzureFunctionsQuickstart-rg --sku Standard_LRS --allow-blob-public-access false
   

   The az storage account create command creates the storage account.

   In the previous example, replace <STORAGE_NAME> with a name that is appropriate to you and unique in Azure Storage. Names must contain three to 24 characters numbers and lowercase letters only. Standard_LRS specifies a general-purpose account, which is supported by Functions.

4. Create the function app in Azure:

   • Azure CLI
   • Azure PowerShell

   az functionapp create --resource-group AzureFunctionsQuickstart-rg --consumption-plan-location <REGION> --runtime node --runtime-version 18 --functions-version 4 --name <APP_NAME> --storage-account <STORAGE_NAME>
   

   The az functionapp create command creates the function app in Azure. It's recommended that you use the latest LTS version of Node.js, which is currently 18. You can specify the version by setting --runtime-version to 18.

   In the previous example, replace <STORAGE_NAME> with the name of the account you used in the previous step, and replace <APP_NAME> with a globally unique name appropriate to you. The <APP_NAME> is also the default DNS domain for the function app.

   This command creates a function app running in your specified language runtime under the Azure Functions Consumption Plan, which is free for the amount of usage you incur here. The command also creates an associated Azure Application Insights instance in the same resource group, with which you can monitor your function app and view logs. For more information, see Monitor Azure Functions. The instance incurs no costs until you activate it.

Deploy the function project to Azure

After you've successfully created your function app in Azure, you're now ready to deploy your local functions project by using the func azure functionapp publish command.

In the following example, replace <APP_NAME> with the name of your app.

func azure functionapp publish <APP_NAME>

The publish command shows results similar to the following output (truncated for simplicity):

...

Getting site publishing info...
Creating archive for current directory...
Performing remote build for functions project.

...

Deployment successful.
Remote build succeeded!
Syncing triggers...
Functions in msdocs-azurefunctions-qs:
    HttpExample - [httpTrigger]
        Invoke url: https://msdocs-azurefunctions-qs.chinacloudsites.cn/api/httpexample

Invoke the function on Azure

Because your function uses an HTTP trigger, you invoke it by making an HTTP request to its URL in the browser or with a tool like curl.

Run the following command to view near real-time streaming logs:

func azure functionapp logstream <APP_NAME> 

In a separate terminal window or in the browser, call the remote function again. A verbose log of the function execution in Azure is shown in the terminal.

Clean up resources

If you continue to the next step and add an Azure Storage queue output binding, keep all your resources in place as you'll build on what you've already done.

Otherwise, use the following command to delete the resource group and all its contained resources to avoid incurring further costs.

az group delete --name AzureFunctionsQuickstart-rg

Remove-AzResourceGroup -Name AzureFunctionsQuickstart-rg

Next steps