const Transaction = {
  init(sender, recipient, funds = 0.0) {
    const _feePercent = 0.5;
    this.sender = sender;
    this.recipient = recipient;
    this.funds = Number(funds);
    this.netTotal = function() {
      return _precisionRound(this.funds * _feePercent, 2);
    }
    function _precisionRound(number, precision) {
      const factor = Math.pow(10, precision);
      return Math.round(number * factor) / factor;
    }
    return this;
  },

  displayTransaction() {
    return `Transaction from ${this.sender} to ${this.recipient} for ${this.funds}`;
  }
}

const HashTransaction = Object.create(Transaction)

HashTransaction.init = function HashTransaction(
  sender, recipient, funds
) {
  Transaction.init.call(this, sender, recipient, funds);
  this.transactionId = this.calculateHash();
  return this;
}

HashTransaction.calculateHash = function calculateHash() {
  const data = [this.sender, this.recipient, this.funds].join('');
  let hash = 0, i = 0;

  while (i < data.length) {
    hash = ((hash << 5) - hash + data.charCodeAt(i++)) << 0;
  }
  return hash ** 2;
}