evmosjs

JS and TS libs for Evmos

Example

Get account information

Get the account number, sequence and pubkey from an address. NOTE: if the address had not sent any transaction to the blockchain, the pubkey value are going to be empty.

import { ethToEvmos } from '@evmos/address-converter'
import { generateEndpointAccount } from '@evmos/provider'

const sender = 'evmos1...'
let destination = '0x....'
// The address must be bech32 encoded
if (destination.split('0x').length == 2) {
  destination = ethToEvmos(destination)
}

// Query the node
const options = {
  method: 'GET',
  headers: { 'Content-Type': 'application/json' },
}

let addrRawData = await fetch(
  `http://127.0.0.1:1317${generateEndpointAccount(sender)}`,
  options,
)
// NOTE: the node returns status code 400 if the wallet doesn't exist, catch that error

let addrData = await addRawData.json()

// Response format at @evmos/provider/rest/account/AccountResponse
/*
  account: {
    '@type': string
    base_account: {
      address: string
      pub_key?: {
        '@type': string
        key: string
      }
      account_number: string
      sequence: string
    }
    code_hash: string
  }
*/

Create a MsgSend Transaction

The transaction can be signed using EIP712 on Metamask and SignDirect on Keplr.

import { createMessageSend } from '@evmos/transactions'

const chain = {
  chainId: 9000,
  cosmosChainId: 'evmos_9000-1',
}

const sender = {
  accountAddress: 'ethm1tfegf50n5xl0hd5cxfzjca3ylsfpg0fned5gqm',
  sequence: 1,
  accountNumber: 9,
  pubkey: 'AgTw+4v0daIrxsNSW4FcQ+IoingPseFwHO1DnssyoOqZ',
}

const fee = {
  amount: '20',
  denom: 'aevmos',
  gas: '200000',
}

const memo = ''

const params = {
  destinationAddress: 'evmos1pmk2r32ssqwps42y3c9d4clqlca403yd9wymgr',
  amount: '1',
  denom: 'aevmos',
}

const msg = createMessageSend(chain, sender, fee, memo, params)

// msg.signDirect is the transaction in Keplr format
// msg.legacyAmino is the transaction with legacy amino
// msg.eipToSign is the EIP712 data to sign with metamask

Signing with Metamask

After creating the transaction we need to send the payload to metamask so it can be signed. With that signature we are going to add a Web3Extension to the Cosmos Transactions and broadcast it to the Evmos node.

// Follow the previous step to generate the msg object
import { evmosToEth } from '@evmos/address-converter'
import {
  generateEndpointBroadcast,
  generatePostBodyBroadcast,
} from '@evmos/provider'
import {
  createTxRawEIP712,
  signatureToWeb3Extension,
} from '@evmos/transactions'

// Init Metamask
await window.ethereum.enable()

// Request the signature
let signature = await window.ethereum.request({
  method: 'eth_signTypedData_v4',
  params: [evmosToEth(sender.accountAddress), JSON.stringify(msg.eipToSign)],
})

// The chain and sender objects are the same as the previous example
let extension = signatureToWeb3Extension(chain, sender, signature)

// Create the txRaw
let rawTx = createTxRawEIP712(
  msg.legacyAmino.body,
  msg.legacyAmino.authInfo,
  extension,
)

// Broadcast it
const postOptions = {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: generatePostBodyBroadcast(rawTx),
}

let broadcastPost = await fetch(
  `http://localhost:1317${generateEndpointBroadcast()}`,
  postOptions,
)
let response = await broadcastPost.json()

Signing with Keplr

// Follow the previous step to generate the msg object
import { createTxRaw } from '@evmos/proto'
import {
  generateEndpointBroadcast,
  generatePostBodyBroadcast,
} from '@evmos/provider'

let sign = await window?.keplr?.signDirect(
  chain.cosmosChainId,
  sender.accountAddress,
  {
    bodyBytes: msg.signDirect.body.serializeBinary(),
    authInfoBytes: msg.signDirect.authInfo.serializeBinary(),
    chainId: chain.cosmosChainId,
    accountNumber: new Long(sender.accountNumber),
  },
  // @ts-expect-error the types are not updated on Keplr side
  { isEthereum: true },
)

if (sign !== undefined) {
  let rawTx = createTxRaw(sign.signed.bodyBytes, sign.signed.authInfoBytes, [
    new Uint8Array(Buffer.from(sign.signature.signature, 'base64')),
  ])

  // Broadcast it
  const postOptions = {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: generatePostBodyBroadcast(rawTx),
  }

  let broadcastPost = await fetch(
    `http://localhost:1317${generateEndpointBroadcast()}`,
    postOptions,
  )
  let response = await broadcastPost.json()
}

TODO

• Add docs and examples to all the packages.
• Add more cosmos messages