Create a Node.js app with the Azure SDK for JavaScript

This document shows examples of how to use the Azure SDK for JavaScript to access key-values in Azure App Configuration.

Tip

App Configuration offers a JavaScript provider library that is built on top of the JavaScript SDK and is designed to be easier to use with richer features. It enables configuration settings to be used like a Map object, and offers other features like configuration composition from multiple labels, key name trimming, and automatic resolution of Key Vault references. Go to the JavaScript quickstart to learn more.

Prerequisites

• An Azure account with an active subscription - Create one for free
• An App Configuration store. Create a store.
• LTS versions of Node.js. For information about installing Node.js either directly on Windows or using the Windows Subsystem for Linux (WSL), see Get started with Node.js

Create a key-value

Add the following key-value to the App Configuration store and leave Label and Content Type with their default values. For more information about how to add key-values to a store using the Azure portal or the CLI, go to Create a key-value.

Key	Value
TestApp:Settings:Message	Data from Azure App Configuration

Setting up the Node.js app

1. In this tutorial, you'll create a new directory for the project named app-configuration-example.

   mkdir app-configuration-example
   

2. Switch to the newly created app-configuration-example directory.

   cd app-configuration-example
   

3. Install the Azure App Configuration client library by using the npm install command.

   npm install @azure/app-configuration
   

4. Create a new file called app-configuration-example.js in the app-configuration-example directory and add the following code:

   const { AppConfigurationClient } = require("@azure/app-configuration");
   
   async function run() {
     console.log("Azure App Configuration - JavaScript example");
     // Example code goes here
   }
   
   run().catch(console.error);
   

Note

The code snippets in this example will help you get started with the App Configuration client library for JavaScript. For your application, you should also consider handling exceptions according to your needs. To learn more about exception handling, please refer to our JavaScript SDK documentation.

Configure your App Configuration connection string

1. Set an environment variable named AZURE_APPCONFIG_CONNECTION_STRING, and set it to the connection string of your App Configuration store. At the command line, run the following command:

   Windows command prompt

   To run the app locally using the Windows command prompt, run the following command and replace <app-configuration-store-connection-string> with the connection string of your app configuration store:

   setx AZURE_APPCONFIG_CONNECTION_STRING "<app-configuration-store-connection-string>"
   

   PowerShell

   If you use Windows PowerShell, run the following command and replace <app-configuration-store-connection-string> with the connection string of your app configuration store:

   $Env:AZURE_APPCONFIG_CONNECTION_STRING = "<app-configuration-store-connection-string>"
   

   macOS

   If you use macOS, run the following command and replace <app-configuration-store-connection-string> with the connection string of your app configuration store:

   export AZURE_APPCONFIG_CONNECTION_STRING='<app-configuration-store-connection-string>'
   

   Linux

   If you use Linux, run the following command and replace <app-configuration-store-connection-string> with the connection string of your app configuration store:

   export AZURE_APPCONFIG_CONNECTION_STRING='<app-configuration-store-connection-string>'
   

2. Print out the value of the environment variable to validate that it is set properly with the command below.

   Windows command prompt

   Using the Windows command prompt, restart the command prompt to allow the change to take effect and run the following command:

   echo %AZURE_APPCONFIG_CONNECTION_STRING%
   

   PowerShell

   If you use Windows PowerShell, run the following command:

   $Env:AZURE_APPCONFIG_CONNECTION_STRING
   

   macOS

   If you use macOS, run the following command:

   echo "$AZURE_APPCONFIG_CONNECTION_STRING"
   

   Linux

   If you use Linux, run the following command:

   echo "$AZURE_APPCONFIG_CONNECTION_STRING"
   

Code samples

The sample code snippets in this section show you how to perform common operations with the App Configuration client library for JavaScript. Add these code snippets to the body of run function in app-configuration-example.js file you created earlier.

Note

The App Configuration client library refers to a key-value object as ConfigurationSetting. Therefore, in this article, the key-values in App Configuration store will be referred to as configuration settings.

Learn below how to:

• Connect to an App Configuration store
• Get a configuration setting
• Add a configuration setting
• Get a list of configuration settings
• Lock a configuration setting
• Unlock a configuration setting
• Update a configuration setting
• Delete a configuration setting

Connect to an App Configuration store

The following code snippet creates an instance of AppConfigurationClient using the connection string stored in your environment variables.

const connection_string = process.env.AZURE_APPCONFIG_CONNECTION_STRING;
const client = new AppConfigurationClient(connection_string);

Get a configuration setting

The following code snippet retrieves a configuration setting by key name.

    const retrievedConfigSetting = await client.getConfigurationSetting({
        key: "TestApp:Settings:Message"
    });
    console.log("\nRetrieved configuration setting:");
    console.log(`Key: ${retrievedConfigSetting.key}, Value: ${retrievedConfigSetting.value}`);

Add a configuration setting

The following code snippet creates a ConfigurationSetting object with key and value fields and invokes the addConfigurationSetting method. This method will throw an exception if you try to add a configuration setting that already exists in your store. If you want to avoid this exception, the setConfigurationSetting method can be used instead.

    const configSetting = {
        key:"TestApp:Settings:NewSetting",
        value:"New setting value"
    };
    const addedConfigSetting = await client.addConfigurationSetting(configSetting);
    console.log("\nAdded configuration setting:");
    console.log(`Key: ${addedConfigSetting.key}, Value: ${addedConfigSetting.value}`);

Get a list of configuration settings

The following code snippet retrieves a list of configuration settings. The keyFilter and labelFilter arguments can be provided to filter key-values based on key and label respectively. For more information on filtering, see how to query configuration settings.

    const filteredSettingsList = client.listConfigurationSettings({
        keyFilter: "TestApp*"
    });
    console.log("\nRetrieved list of configuration settings:");
    for await (const filteredSetting of filteredSettingsList) {
        console.log(`Key: ${filteredSetting.key}, Value: ${filteredSetting.value}`);
    }

Lock a configuration setting

The lock status of a key-value in App Configuration is denoted by the readOnly attribute of the ConfigurationSetting object. If readOnly is true, the setting is locked. The setReadOnly method can be invoked with true as the second argument to lock the configuration setting.

    const lockedConfigSetting = await client.setReadOnly(addedConfigSetting, true /** readOnly */);
    console.log(`\nRead-only status for ${lockedConfigSetting.key}: ${lockedConfigSetting.isReadOnly}`);

Unlock a configuration setting

If the readOnly attribute of a ConfigurationSetting is false, the setting is unlocked. The setReadOnly method can be invoked with false as the second argument to unlock the configuration setting.

    const unlockedConfigSetting = await client.setReadOnly(lockedConfigSetting, false /** readOnly */);
    console.log(`\nRead-only status for ${unlockedConfigSetting.key}: ${unlockedConfigSetting.isReadOnly}`);

Update a configuration setting

The setConfigurationSetting method can be used to update an existing setting or create a new setting. The following code snippet changes the value of an existing configuration setting.

    addedConfigSetting.value = "Value has been updated!";
    const updatedConfigSetting = await client.setConfigurationSetting(addedConfigSetting);
    console.log("\nUpdated configuration setting:");
    console.log(`Key: ${updatedConfigSetting.key}, Value: ${updatedConfigSetting.value}`);

Delete a configuration setting

The following code snippet deletes a configuration setting by key name.

    const deletedConfigSetting = await client.deleteConfigurationSetting({
        key: "TestApp:Settings:NewSetting"
    });
    console.log("\nDeleted configuration setting:");
    console.log(`Key: ${deletedConfigSetting.key}, Value: ${deletedConfigSetting.value}`);

Run the app

In this example, you created a Node.js app that uses the Azure App Configuration client library to retrieve a configuration setting created through the Azure portal, add a new setting, retrieve a list of existing settings, lock and unlock a setting, update a setting, and finally delete a setting.

At this point, your app-configuration-example.js file should have the following code:

const { AppConfigurationClient } = require("@azure/app-configuration");

async function run() {
    console.log("Azure App Configuration - JavaScript example");

    const connection_string = process.env.AZURE_APPCONFIG_CONNECTION_STRING;
    const client = new AppConfigurationClient(connection_string);

    const retrievedConfigSetting = await client.getConfigurationSetting({
        key: "TestApp:Settings:Message"
    });
    console.log("\nRetrieved configuration setting:");
    console.log(`Key: ${retrievedConfigSetting.key}, Value: ${retrievedConfigSetting.value}`);

    const configSetting = {
        key: "TestApp:Settings:NewSetting",
        value: "New setting value"
    };
    const addedConfigSetting = await client.addConfigurationSetting(configSetting);
    console.log("Added configuration setting:");
    console.log(`Key: ${addedConfigSetting.key}, Value: ${addedConfigSetting.value}`);

    const filteredSettingsList = client.listConfigurationSettings({
        keyFilter: "TestApp*"
    });
    console.log("Retrieved list of configuration settings:");
    for await (const filteredSetting of filteredSettingsList) {
        console.log(`Key: ${filteredSetting.key}, Value: ${filteredSetting.value}`);
    }

    const lockedConfigSetting = await client.setReadOnly(addedConfigSetting, true /** readOnly */);
    console.log(`Read-only status for ${lockedConfigSetting.key}: ${lockedConfigSetting.isReadOnly}`);

    const unlockedConfigSetting = await client.setReadOnly(lockedConfigSetting, false /** readOnly */);
    console.log(`Read-only status for ${unlockedConfigSetting.key}: ${unlockedConfigSetting.isReadOnly}`);

    addedConfigSetting.value = "Value has been updated!";
    const updatedConfigSetting = await client.setConfigurationSetting(addedConfigSetting);
    console.log("Updated configuration setting:");
    console.log(`Key: ${updatedConfigSetting.key}, Value: ${updatedConfigSetting.value}`);

    const deletedConfigSetting = await client.deleteConfigurationSetting({
        key: "TestApp:Settings:NewSetting"
    });
    console.log("Deleted configuration setting:");
    console.log(`Key: ${deletedConfigSetting.key}, Value: ${deletedConfigSetting.value}`);
}

run().catch(console.error);

In your console window, navigate to the directory containing the app-configuration-example.js file and execute the following command to run the app:

node app.js

You should see the following output:

Azure App Configuration - JavaScript example

Retrieved configuration setting:
Key: TestApp:Settings:Message, Value: Data from Azure App Configuration

Added configuration setting:
Key: TestApp:Settings:NewSetting, Value: New setting value

Retrieved list of configuration settings:
Key: TestApp:Settings:Message, Value: Data from Azure App Configuration
Key: TestApp:Settings:NewSetting, Value: New setting value

Read-only status for TestApp:Settings:NewSetting: true

Read-only status for TestApp:Settings:NewSetting: false

Updated configuration setting:
Key: TestApp:Settings:NewSetting, Value: Value has been updated!

Deleted configuration setting:
Key: TestApp:Settings:NewSetting, Value: Value has been updated!

Clean up resources

If you don't want to continue using the resources created in this article, delete the resource group you created here to avoid charges.

Important

Deleting a resource group is irreversible. The resource group and all the resources in it are permanently deleted. Ensure that you don't accidentally delete the wrong resource group or resources. If you created the resources for this article inside a resource group that contains other resources you want to keep, delete each resource individually from its respective pane instead of deleting the resource group.

1. Sign in to the Azure portal, and select Resource groups.
2. In the Filter by name box, enter the name of your resource group.
3. In the result list, select the resource group name to see an overview.
4. Select Delete resource group.
5. You're asked to confirm the deletion of the resource group. Enter the name of your resource group to confirm, and select Delete.

After a few moments, the resource group and all its resources are deleted.

Next steps

This guide showed you how to use the Azure SDK for JavaScript to access key-values in Azure App Configuration.

For additional code samples, visit:

Azure App Configuration client library samples

To learn how to use Azure App Configuration with JavaScript apps, go to:

Create a JavaScript app with Azure App Configuration