Revised Cart component

Cart.js

import React, { Component } from 'react';
import Total from './Total';

const USCurrencyFormat = new Intl.NumberFormat('en-US', {
  style: 'currency',
  currency: 'USD'
});

class Cart extends Component {

  constructor(props) {
    super(props);
  }

 render() {
   let summary = null;
   if (this.props == null || this.props.selected == null) {
      summary = "";
   } else {
    const summary = Object.keys(this.props.selected).map((feature, idx) => {
      const featureHash = feature + '-' + idx;
      const selectedOption = this.props.selected[feature];
      return (
        <div className="summary__option" key={featureHash}>
          <div className="summary__option__label">{feature} </div>
          <div className="summary__option__value">{selectedOption.name}</div>
          <div className="summary__option__cost">
            {USCurrencyFormat.format(selectedOption.cost)}
          </div>
        </div>
      );
    });
  }
  return (
    <section className="main__summary">
      <h2>Your cart</h2>
      {summary}
      <Total selected={this.props.selected}/>
    </section>
  )
 }
}

export default Cart;