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Access a user's MetaMask provider

You the metamask-extension-provider package to access a user's MetaMask provider from other web extensions.

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

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

This module works in Chrome and Firefox.

Installation​

npm install metamask-extension-provider -s

Usage​

You can use a bundler such as Browserify with metamask-extension-provider.

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

const provider = createMetaMaskProvider();

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

// Enjoy!

Add additional browser support​

Add MetaMask's extension ID for that browser's store to the configuration file:

{
  "CHROME_ID": "nkbihfbeogaeaoehlefnkodbefgpgknn",
  "FIREFOX_ID": "webextension@metamask.io"
}

Run the example​

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

Edit the example​

You must have Browserify installed (npm i -g browserify) to edit the example.

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

Use with a local development copy of MetaMask​

You must edit the method getMetaMaskId() to return your local development MetaMask instance's ID. You can get that from your MetaMask console using chrome.runtime.id.

Current limitations​

In order to identify problems (such as MetaMask not connecting), 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.