firebase-js-sdk/README.md

# Firebase JavaScript SDK

<!-- BADGES -->
![Build Status](https://img.shields.io/github/actions/workflow/status/firebase/firebase-js-sdk/test-all.yml)
[![Version](https://img.shields.io/npm/v/firebase.svg?label=version)](https://www.npmjs.com/package/firebase)
[![Coverage Status](https://coveralls.io/repos/github/firebase/firebase-js-sdk/badge.svg?branch=main)](https://coveralls.io/github/firebase/firebase-js-sdk?branch=main)
<!-- END BADGES -->

The Firebase JavaScript SDK implements the client-side libraries used by
applications using Firebase services. This SDK is distributed via:

- [CDN](https://firebase.google.com/docs/web/setup/#add-sdks-initialize)
- [npm package](https://www.npmjs.com/package/firebase)

To get started using Firebase, see
[Add Firebase to your JavaScript Project](https://firebase.google.com/docs/web/setup).

[![Release Notes](https://img.shields.io/npm/v/firebase.svg?style=flat-square&label=Release%20Notes%20for&labelColor=039be5&color=666)](https://firebase.google.com/support/release-notes/js)

## Upgrade to Version 9

Version 9 has a redesigned API that supports tree-shaking. Read the [Upgrade Guide](https://firebase.google.com/docs/web/modular-upgrade) to learn more.

## Supported Environments

Please see [Environment Support](https://firebase.google.com/support/guides/environments_js-sdk).

## SDK Dev Workflow

### Prerequisites

#### Node.js

Before you can start working on the Firebase JS SDK, you need to have Node.js
installed on your machine. As of July 17th, 2026 the team has been testing with Node.js version 
`20.19.0`, but the required version of Node.js may change as we update our dependencies.

To download Node.js visit https://nodejs.org/en/download/.

_NOTE: You can use a tool like [`NVM`](https://github.com/creationix/nvm)
or [`N`](https://github.com/tj/n) to install and manage multiple node versions_

#### Yarn

In addition to Node.js we use `yarn` to facilitate multi package development.

To install `yarn` follow the instructions listed on their website:
https://yarnpkg.com/en/docs/install

This repo currently supports building with yarn `1.x`. For instance, after installing yarn, run
```bash
$ yarn set version 1.22.11
```

#### Java

The closure compiler requires a modern Java installation. Java 11+ should be installed: https://www.oracle.com/java/technologies/downloads/#java11

#### Verify Prerequisites

You can verify your setup by running the following commands in your terminal:

```bash
$ node -v
$ yarn -v
$ java -version
```

Your `node` version should be `20.19.0` or greater, your `yarn` version should
be between `1.0.0` and `1.22.11`, and your `java` version should be `11.0` or greater.

_NOTE: We will update the documentation as new versions are required, however
for continuing development on the SDK, staying up to date on the stable versions
of these packages is advised_

### Install Dependencies

Once you have Node.js and `yarn` installed on your machine and have validated
that you are running the proper version, you can set up the development environment
by running the following at the root of the SDK:

```bash
$ yarn
```

Once you have installed all the dependencies, you can build the entire SDK by
running the following command the root of the SDK:

```bash
$ yarn build
```

## Testing the SDK

### Test Setup

A production project is required to test the Firebase JS SDK. You can create a
new project by visiting the [Firebase Console](https://console.firebase.google.com/).

#### Web App Setup

Visit the "Project Overview" and select "Add app" under your project name. Register the app with a
nickname and click through the remaining steps. Without performing this step, you will encounter
the error in the test setup:

```
FirebaseError: There are no WEB apps associated with this Firebase project
```

#### Firestore Database Setup

Visit the "Firestore Database" section of the console and create a Cloud Firestore
database. When prompted to select the set of initial security rules, select
any option (e.g. "Start in Production Mode") since these permission settings
will be overwritten below.

#### Realtime Database Setup

Visit the "Realtime Database" section of the console and create a realtime
database. When prompted to select the set of initial security rules, select
any option (e.g. "Start in Locked Mode") since these permission settings
will be overwritten below.

#### Storage Setup

Visit the "Storage" section of the console and create a storage bucket. In 
order to run the tests, you will need to update your bucket's CORS rules.

1. Create a new file called `cors.json` with the contents:
```json
[
    {
        "origin": ["http://localhost:8089"],
        "method": ["GET"],
        "maxAgeSeconds": 3600
    }
]
```
1. Install `gsutil` from https://cloud.google.com/storage/docs/gsutil_install
1. You will need to login if this is your first time using `gsutil`. Run `gcloud auth login`
and follow the instructions to login.
1. Run `gcloud storage buckets update gs://<your-cloud-storage-bucket> --cors-file=cors.json`

For more information, visit https://firebase.google.com/docs/storage/web/download-files#cors_configuration

Then, make sure you have anonymous sign-in provider enabled:

#### Authentication Support

Visit the authentication config in your project and enable the `Anonymous`
sign-in provider to complete your project config.

#### Automated Setup

The tests need to be configured to use the Firebase production project that you
created in the "Test Setup" section above. To do this, run the `yarn test:setup`
command, as follows:


```bash
# Select the Firebase project via the text-based UI. This will run tools/config.js
# and deploy from config/ to your Firebase project.
$ yarn test:setup

# Specify the Firebase project via the command-line arguments.
$ yarn test:setup --projectId=<test_firebase_project_id>
```

If you see an error like
```
HTTP Error: 404, Project '<test_firebase_project_id>' does not exist.
```
then make sure that you have created the database as specified in the "Firestore
Database Setup" section above.

### Running the tests

Each of the directories in the `integration` directory as well as the `packages`
directory have their own test suites. You will need to build the SDK before
running tests. Test suites can be run all together by running the following 
command at the root of the package:

```bash
$ yarn test
```

In addition, you can run any of the tests individually by running `yarn test` in
an individual package directory.

## Building the SDK

### Introduction

The Firebase JS SDK is built with a series of individual packages that are all
contained in this repository. Development is coordinated via [yarn
workspaces](https://yarnpkg.com/blog/2017/08/02/introducing-workspaces/) and
[Lerna](https://lerna.js.org/) (a monorepo management tool).

Each package in the `packages` directory, constitute a piece of our
implementation. The SDK is built via a combination of all of these packages
which are published under the [`firebase`
scope](https://www.npmjs.com/search?q=scope%3Afirebase) on NPM.

### Testing the SDK Locally

Please be sure your product's package has been built before proceeding any further. (If you haven't built this repo before, make sure to run `yarn build` at the root)
In order to manually test your SDK changes locally, you must use [yarn link](https://classic.yarnpkg.com/en/docs/cli/link):

```shell
$ cd packages/firebase
$ yarn link # initialize the linking to the other folder
$ cd ../<my-product> # Example: $ cd ../firestore
$ yarn link # link your product to make it available elsewhere
$ cd <my-test-app-dir> # cd into your personal project directory
$ yarn link firebase @firebase/<my-product> # tell yarn to use the locally built firebase SDK instead
```

This will create a symlink and point your `<my-test-app-dir>` to the locally built version of the firebase SDK.

### Helper Scripts

Each package in the `packages` directory exposes a `dev` script. This script
will set up a watcher for development on the individual piece of the SDK. In
addition, there is a top level `dev` script that can be run to start all of the
watch tasks as well as a sandbox server.

You can run the dev script by running the following at the root of the package:

```bash
$ yarn dev
```

### Prepush Hooks

As part of this repo, we use the NPM package [`husky`](https://npm.im/husky) to
implement git hooks. We leverage the prepush hook to do two things:

- Automated code styling (using [`prettier`](https://npm.im/prettier))
- Automated LICENSE header insertion

## Contributing

See [Contributing](./CONTRIBUTING.md) for more information on contributing to the Firebase
JavaScript SDK.