Get started with Firebase Remote Config

You can use Firebase Remote Config to define parameters in your app and update their values in the cloud, allowing you to modify the appearance and behavior of your app without distributing an app update. This guide walks you through the steps to get started and provides some sample code, all of which is available to clone or download from the firebase/quickstart-js GitHub repository.

Step 1: Add and initialize the Remote Config SDK

1. If you haven't already, install the Firebase JS SDK and initialize Firebase.

2. Add the Remote Config JS SDK and initialize Remote Config:

import { initializeApp } from "firebase/app";
import { getRemoteConfig } from "firebase/remote-config";

// TODO: Replace the following with your app's Firebase project configuration
// See: https://firebase.google.com/docs/web/learn-more#config-object
const firebaseConfig = {
  // ...
};

// Initialize Firebase
const app = initializeApp(firebaseConfig);


// Initialize Remote Config and get a reference to the service
const remoteConfig = getRemoteConfig(app);

import firebase from "firebase/compat/app";
import "firebase/compat/remote-config";

// TODO: Replace the following with your app's Firebase project configuration
// See: https://firebase.google.com/docs/web/learn-more#config-object
const firebaseConfig = {
  // ...
};

// Initialize Firebase
firebase.initializeApp(firebaseConfig);


// Initialize Remote Config and get a reference to the service
const remoteConfig = firebase.remoteConfig();

This object is used to store in-app default parameter values, fetch updated parameter values from the Remote Config backend, and control when fetched values are made available to your app.

Step 2: Set minimum fetch interval

During development, it's recommended to set a relatively low minimum fetch interval. See Throttling for more information.

remoteConfig.settings.minimumFetchIntervalMillis = 3600000;
rc_set_minimum_fetch_time.js

remoteConfig.settings.minimumFetchIntervalMillis = 3600000;
index.js

Step 3: Set in-app default parameter values

You can set in-app default parameter values in the Remote Config object, so that your app behaves as intended before it connects to the Remote Config backend, and so that default values are available if none are set on the backend.

remoteConfig.defaultConfig = {
  "welcome_message": "Welcome"
};
rc_set_default_values.js

remoteConfig.defaultConfig = {
  "welcome_message": "Welcome"
};
index.js

If you have already configured Remote Config backend parameter values, you can download a generated JSON file that includes all default values and include it in your app bundle:

curl --compressed -D headers -H "Authorization: Bearer token" -X GET https://firebaseremoteconfig.googleapis.com/v1/projects/my-project-id/remoteConfig:downloadDefaults?format=JSON -o remote_config_defaults.json

The following examples show two different ways you could import and set default values in your app. The first example uses fetch, which will make an HTTP request to the defaults file included in your app bundle:

  const rcDefaultsFile = await fetch('remote_config_defaults.json');
  const rcDefaultsJson = await rcDefaultsFile.json();
  remoteConfig.defaultConfig = rcDefaultsJson;
  

The next example uses require, which compiles the values into your app at build time:

  let rcDefaults = require('./remote_config_defaults.json');
  remoteConfig.defaultConfig = rcDefaults;

Step 4: Get parameter values to use in your app

Now you can get parameter values from the Remote Config object. If you later set values in the backend, fetch them, and then activate them, those values are available to your app.To get these values, call the getValue() method, providing the parameter key as an argument.

import { getValue } from "firebase/remote-config";

const val = getValue(remoteConfig, "welcome_messsage");
rc_get_values.js

const val = remoteConfig.getValue("welcome_messsage");
index.js

Step 5: Set parameter values

Using the Firebase console or the Remote Config backend APIs, you can create new server-side default values that override the in-app values according to your desired conditional logic or user targeting. This section walks you through the Firebase console steps to create these values.

1. In the Firebase console, open your project.
2. Select Remote Config from the menu to view the Remote Config dashboard.
3. Define parameters with the same names as the parameters that you defined in your app. For each parameter, you can set a default value (which will eventually override the in-app default value) and you can also set conditional values. To learn more, see Remote Config Parameters and Conditions.

Step 6: Fetch and activate values

1. To fetch parameter values from the Remote Config backend, call the fetchConfig() method. Any values that you set on the backend are fetched and cached in the Remote Config object.
2. To make fetched parameter values available to your app, call the activate() method.

For cases where you want to fetch and activate values in one call, use fetchAndActivate() as shown in this example:

import { fetchAndActivate } from "firebase/remote-config";

fetchAndActivate(remoteConfig)
  .then(() => {
    // ...
  })
  .catch((err) => {
    // ...
  });
rc_fetch_config_callback.js

remoteConfig.fetchAndActivate()
  .then(() => {
    // ...
  })
  .catch((err) => {
    // ...
  });
index.js

Because these updated parameter values affect the behavior and appearance of your app, you should activate the fetched values at a time that ensures a smooth experience for your user, such as the next time that the user opens your app. See Remote Config loading strategies for more information and examples.

Throttling

If an app fetches too many times in a short time period, fetch calls may be throttled. In such cases, the SDK throws a FETCH_THROTTLE error. You are recommended to catch this error and retry in exponential backoff mode, waiting longer intervals between subsequent fetch requests.

During app development, you might want to refresh the cache very frequently (many times per hour) to let you rapidly iterate as you develop and test your app. To accommodate rapid iteration on a project with numerous developers, you can temporarily add a property with a low minimum fetch interval (Settings.minimumFetchIntervalMillis) in your app.

The default and recommended production fetch interval for Remote Config is 12 hours, which means that configs won't be fetched from the backend more than once in a 12 hour window, regardless of how many fetch calls are actually made. Specifically, the minimum fetch interval is determined in the following order:

1. The parameter in Settings.minimumFetchIntervalMillis.
2. The default value of 12 hours.

Next steps

If you haven't already, explore the Remote Config use cases, and take a look at some of the key concepts and advanced strategies documentation, including:

• Manage Remote Config template versions
• Config loading strategies