Add query balance function

App.vue

<!-- Continue with the App.vue -->
<script>
const operations = require('./operations.js')
const utils = require('./utils.js')

export default {
  data() {
    return {
      myaddress: '0xa7a609b928c4eac077d0e5640f3fa650746c4fcf',
      myamount: 0,
      contract: '0x0000000000000000000000000000456e65726779'
    }
  },
  beforeMount () {
    this.refreshTokenBalance()
  },
  methods: {
    refreshTokenBalance () {
      operations.getTokenBalance(this.contract, this.myaddress)
        .then(result => {
          this.myamount = utils.evmToPrintable(result['decoded']['balance'], this.decimals)
        })
        .then(() => {
          // eslint-disable-next-line
          const ticker = connex.thor.ticker()
          ticker.next().then(() => { this.refreshTokenBalance() })
        })
    }
  }
}
</script>