MetaMask Plugin

Developing Compatible Dapps

If you're a web dapp developer, we've got two types of guides for you:

• If you've never built a Dapp before, we've got a gentle introduction on Developing Dapps with Truffle and MetaMask.
• If you have a Dapp, and you want to ensure compatibility, here is our guide on building MetaMask-compatible Dapps

Building locally

• Install Node.js version 6.3.1 or later.
• Install local dependencies with npm install.
• Install gulp globally with npm install -g gulp-cli.
• Build the project to the ./dist/ folder with gulp build.
• Optionally, to rebuild on file changes, run gulp dev.
• To package .zip files for distribution, run gulp zip, or run the full build & zip with gulp dist.

Uncompressed builds can be found in /dist, compressed builds can be found in /builds once they're built.

Architecture

Development

npm install

In Chrome

Open Settings > Extensions.

Check "Developer mode".

At the top, click Load Unpacked Extension.

Navigate to your metamask-plugin/dist/chrome folder.

Click Select.

You now have the plugin, and can click 'inspect views: background plugin' to view its dev console.

In Firefox

Go to the url about:debugging.

Click the button Load Temporary Add-On.

Select the file dist/firefox/manifest.json.

You can optionally enable debugging, and click Debug, for a console window that logs all of Metamask's processes to a single console.

If you have problems debugging, try connecting to the IRC channel #webextensions on irc.mozilla.org.

For longer questions, use the StackOverfow tag firefox-addons.

Developing on UI Only

You can run npm run ui, and your browser should open a live-reloading demo version of the plugin UI.

Some actions will crash the app, so this is only for tuning aesthetics, but it allows live-reloading styles, which is a much faster feedback loop than reloading the full extension.

Developing on UI with Mocked Background Process

You can run npm run mock and your browser should open a live-reloading demo version of the plugin UI, just like the npm run ui, except that it tries to actually perform all normal operations.

It does not yet connect to a real blockchain (this could be a good test feature later, connecting to a test blockchain), so only local operations work.

You can reset the mock ui at any time with the Reset button at the top of the screen.

Developing on Dependencies

To enjoy the live-reloading that gulp dev offers while working on the web3-provider-engine or other dependencies:

1. Clone the dependency locally.
2. npm install in its folder.
3. Run npm link in its folder.
4. Run npm link $DEP_NAME in this project folder.
5. Next time you gulp dev it will watch the dependency for changes as well!

Running Tests

Requires mocha installed. Run npm install -g mocha.

Then just run npm test.

You can also test with a continuously watching process, via npm run watch.

You can run the linter by itself with gulp lint.

Writing Browser Tests

To write tests that will be run in the browser using QUnit, add your test files to test/integration/lib.

Deploying the UI

You must be authorized already on the MetaMask plugin.

0. Update the version in app/manifest.json and the Changelog in CHANGELOG.md.
1. Visit the chrome developer dashboard.
2. Run gulp dist (or gulp zip if you've already built)
3. Upload the latest zip file from builds/metamask-$PLATFORM-$VERSION.zip as the updated package.