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title description ms.date ms.topic ms.devlang ms.custom zone_pivot_groups
Create a JavaScript function from the command line - Azure Functions
Learn how to create a JavaScript function from the command line, then publish the local Node.js project to serverless hosting in Azure Functions.
03/08/2023
quickstart
javascript
devx-track-azurecli, devx-track-azurepowershell, mode-api, devx-track-js
functions-nodejs-model

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.

[!INCLUDE functions-nodejs-model-pivot-description]

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:

::: zone pivot="nodejs-model-v3"

::: zone pivot="nodejs-model-v4"

::: zone pivot="nodejs-model-v3"

  • Node.js version 18 or 16. ::: zone-end

::: zone pivot="nodejs-model-v4"

  • Node.js version 18 or above. ::: zone-end

Prerequisite check

Verify your prerequisites, which depend on whether you're using Azure CLI or Azure PowerShell for creating Azure resources:

Azure CLI

::: zone pivot="nodejs-model-v3"

  • In a terminal or command window, run func --version to check that the Azure Functions Core Tools are version 4.x. ::: zone-end

::: zone pivot="nodejs-model-v4"

  • In a terminal or command window, run func --version to check that the Azure Functions Core Tools are version v4.0.5095 or above. ::: zone-end

  • Run az --version to check that the Azure CLI version is 2.4 or later.

  • Run az login to sign in to Azure and verify an active subscription.

Azure PowerShell

::: zone pivot="nodejs-model-v3"

  • In a terminal or command window, run func --version to check that the Azure Functions Core Tools are version 4.x. ::: zone-end

::: zone pivot="nodejs-model-v4"

  • In a terminal or command window, run func --version to check that the Azure Functions Core Tools are version v4.0.5095 or above. ::: zone-end

  • Run (Get-Module -ListAvailable Az).Version and verify version 5.0 or later.

  • Run Connect-AzAccount to sign in to Azure and verify an active subscription.

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.

::: zone pivot="nodejs-model-v3"

  1. Run the func init command, as follows, to create a functions project in a folder named LocalFunctionProj with the specified runtime:

    func init LocalFunctionProj --javascript

  2. Navigate into the project folder:

    cd LocalFunctionProj

    This folder contains various files for the project, including configurations files named local.settings.json and host.json. Because local.settings.json can contain secrets downloaded from Azure, the file is excluded from source control by default in the .gitignore file.

  3. Add a function to your project by using the following command, where the --name argument is the unique name of your function (HttpExample) and the --template argument specifies the function's trigger (HTTP).

    func new --name HttpExample --template "HTTP trigger" --authlevel "anonymous"

    func new creates a subfolder matching the function name that contains a code file appropriate to the project's chosen language and a configuration file named function.json.

You may find the Azure Functions Core Tools reference helpful.

(Optional) Examine the file contents

If desired, you can skip to Run the function locally and examine the file contents later.

index.js

index.js exports a function that's triggered according to the configuration in function.json.

:::code language="javascript" source="~/functions-quickstart-templates/Functions.Templates/Templates/HttpTrigger-JavaScript/index.js":::

For an HTTP trigger, the function receives request data in the variable req as defined in function.json. The response is defined as res in function.json and can be accessed using context.res. To learn more, see Azure Functions HTTP triggers and bindings.

function.json

function.json is a configuration file that defines the input and output bindings for the function, including the trigger type.

:::code language="json" source="~/functions-quickstart-templates/Functions.Templates/Templates/HttpTrigger-JavaScript/function.json":::

Each binding requires a direction, a type, and a unique name. The HTTP trigger has an input binding of type httpTrigger and output binding of type http.

::: zone-end

::: zone pivot="nodejs-model-v4"

  1. Run the func init command, as follows, to create a functions project in a folder named LocalFunctionProj:

    func init LocalFunctionProj --model V4

    You're then prompted to choose a worker runtime and a language - choose Node for the first and JavaScript for the second.

  2. Navigate into the project folder:

    cd LocalFunctionProj

    This folder contains various files for the project, including configurations files named local.settings.json and host.json. Because local.settings.json can contain secrets downloaded from Azure, the file is excluded from source control by default in the .gitignore file.

  3. Add a function to your project by using the following command:

    func new

    Choose the template for "HTTP trigger". You can keep the default name (httpTrigger) or give it a new name (HttpExample). Your function name must be unique, or you're asked to confirm if your intention is to replace an existing function.

    You can find the function you added in the src/functions directory.

  4. Add Azure Storage connection information in local.settings.json.

    {
    "Values": {       
        "AzureWebJobsStorage": "<Azure Storage connection information>",
        "FUNCTIONS_WORKER_RUNTIME": "node",
        "AzureWebJobsFeatureFlags": "EnableWorkerIndexing"
    }
}

  5. (Optional) If you want to learn more about a particular function, say HTTP trigger, you can run the following command:

    func help httptrigger

::: zone-end

[!INCLUDE functions-run-function-test-local-cli]

[!INCLUDE functions-create-azure-resources-cli]

  1. Create the function app in Azure:

    Azure CLI

    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 version of Node.js, which is currently 18. You can specify the version by setting --runtime-version to 18.

    Azure PowerShell

    New-AzFunctionApp -Name <APP_NAME> -ResourceGroupName AzureFunctionsQuickstart-rg -StorageAccount <STORAGE_NAME> -Runtime node -RuntimeVersion 18 -FunctionsVersion 4 -Location <REGION>

    The New-AzFunctionApp cmdlet creates the function app in Azure. It's recommended that you use the latest 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.

::: zone pivot="nodejs-model-v4"

Update app settings

To enable your V4 programming model app to run in Azure, you need to add a new application setting named AzureWebJobsFeatureFlags with a value of EnableWorkerIndexing. This setting is already in your local.settings.json file.

Run the following command to add this setting to your new function app in Azure. Replace <FUNCTION_APP_NAME> and <RESOURCE_GROUP_NAME> with the name of your function app and resource group, respectively.

Azure CLI

az functionapp config appsettings set --name <FUNCTION_APP_NAME> --resource-group <RESOURCE_GROUP_NAME> --settings AzureWebJobsFeatureFlags=EnableWorkerIndexing

Azure PowerShell

Update-AzFunctionAppSetting -Name <FUNCTION_APP_NAME> -ResourceGroupName <RESOURCE_GROUP_NAME> -AppSetting @{"AzureWebJobsFeatureFlags" = "EnableWorkerIndexing"}

::: zone-end

[!INCLUDE functions-publish-project-cli]

[!INCLUDE functions-run-remote-azure-cli]

[!INCLUDE functions-streaming-logs-cli-qs]

[!INCLUDE functions-cleanup-resources-cli]

Next steps

[!div class="nextstepaction"] Connect to an Azure Storage queue