Use Array.includes

app/scripts/metamask-controller.js

@@ -50,6 +50,7 @@ const seedPhraseVerifier = require('./lib/seed-phrase-verifier')
 const log = require('loglevel')
 const TrezorKeyring = require('eth-trezor-keyring')
 const LedgerBridgeKeyring = require('eth-ledger-bridge-keyring')
+const HW_WALLETS_KEYRINGS = [TrezorKeyring.type, LedgerBridgeKeyring.type]
 const EthQuery = require('eth-query')
 const ethUtil = require('ethereumjs-util')
 const sigUtil = require('eth-sig-util')
@@ -1021,15 +1022,14 @@ module.exports = class MetamaskController extends EventEmitter {
     log.info('MetaMaskController - eth_signTypedData')
     const msgId = msgParams.metamaskId
     const version = msgParams.version
-    const HW_WALLETS_KEYRINGS = [TrezorKeyring.type, LedgerBridgeKeyring.type]
     try {
       const cleanMsgParams = await this.typedMessageManager.approveMessage(msgParams)
       const address = sigUtil.normalize(cleanMsgParams.from)
       const keyring = await this.keyringController.getKeyringForAccount(address)
       let signature
-      // HW Wallet keyrings don't expose private keys so
-      // we need to handle it separately
-      if (HW_WALLETS_KEYRINGS.indexOf(keyring.type) === -1) {
+      // HW Wallet keyrings don't expose private keys
+      // so we need to handle it separately
+      if (!HW_WALLETS_KEYRINGS.includes(keyring.type)) {
         const wallet = keyring._getWalletForAccount(address)
         const privKey = ethUtil.toBuffer(wallet.getPrivateKey())
         switch (version) {