All you should need to do is run this command in the project directory:

node_modules\.bin\browserify index.js > bundle.js

However, you can make things a little more convinient by adding an entry under scripts in your package.json:

{
    ...
    "scripts": {
        "bundle": "browserify index.js > bundle.js"
    }
}

You can then build the bundle with this command:

npm run bundle