whaletogether / extension-provider

A module for allowing a WebExtension to access the web3 provider from an installed MetaMask instance

MetaMask Extension Provider

A module for providing a MetaMask provider to other WebExtensions.

The account provided by this provider will be the user's MetaMask account.

When sending signing requests to this provider, MetaMask will prompt the user to sign with their accounts.

Works in:

• Chrome
• Firefox

Installation

Using npm as a package manager:

npm install metamask-extension-provider -S

Usage

Using a bundler like browserify:

const createMetaMaskProvider = require('metamask-extension-provider')

const provider = createMetaMaskProvider()

provider.on('error', (error) => {
  // Failed to connect to MetaMask, fallback logic.
})

// Enjoy!

Adding additional browser support

Simply add MetaMask's extension ID for that browser's store to the config file.

Running the example

Use the ./sample-extension folder as an WebExtension. You can easily add it to Chrome or Firefox Developer Edition.

Editing the example

You must have browserify installed (npm i -g browserify).

You can edit the sample file sample-extension/index.js and then rebuild the file with npm run buildSample.

Using with a local Development copy of MetaMask

You'll need to edit the method getMetaMaskId() to return your local development MetaMask's id. You can get that from your MetaMask console with chrome.runtime.id.

Current Limitations

In order to identify when there is a problem (like MetaMask was not connected), some kind of proper error handling must be added to metamask-inpage-provider that exposes the errors to the consumer of the provider. Maybe making it an event-emitter, so it can emit its errors, instead of just logging them.