metamask-extension/app/scripts/inpage.js

/*global Web3*/
cleanContextForImports()
require('web3/dist/web3.min.js')
const log = require('loglevel')
const LocalMessageDuplexStream = require('post-message-stream')
// const PingStream = require('ping-pong-stream/ping')
// const endOfStream = require('end-of-stream')
const setupDappAutoReload = require('./lib/auto-reload.js')
const MetamaskInpageProvider = require('./lib/inpage-provider.js')
restoreContextAfterImports()

const METAMASK_DEBUG = process.env.METAMASK_DEBUG
window.log = log
log.setDefaultLevel(METAMASK_DEBUG ? 'debug' : 'warn')


//
// setup plugin communication
//

// setup background connection
var metamaskStream = new LocalMessageDuplexStream({
  name: 'inpage',
  target: 'contentscript',
})

// compose the inpage provider
var inpageProvider = new MetamaskInpageProvider(metamaskStream)

//
// setup web3
//

if (typeof window.web3 !== 'undefined') {
  throw new Error(`MetaMask detected another web3.
     MetaMask will not work reliably with another web3 extension.
     This usually happens if you have two MetaMasks installed,
     or MetaMask and another web3 extension. Please remove one
     and try again.`)
}
var web3 = new Web3(inpageProvider)
web3.setProvider = function () {
  log.debug('MetaMask - overrode web3.setProvider')
}
log.debug('MetaMask - injected web3')
// export global web3, with usage-detection
setupDappAutoReload(web3, inpageProvider.publicConfigStore)

// set web3 defaultAccount

inpageProvider.publicConfigStore.subscribe(function (state) {
  web3.eth.defaultAccount = state.selectedAddress
})

//
// util
//

// need to make sure we aren't affected by overlapping namespaces
// and that we dont affect the app with our namespace
// mostly a fix for web3's BigNumber if AMD's "define" is defined...
var __define

function cleanContextForImports () {
  __define = global.define
  try {
    global.define = undefined
  } catch (_) {
    console.warn('MetaMask - global.define could not be deleted.')
  }
}

function restoreContextAfterImports () {
  try {
    global.define = __define
  } catch (_) {
    console.warn('MetaMask - global.define could not be overwritten.')
  }
}