Redux - Selector

Cart.jsx

import React from 'react'
import { connect } from 'react-redux'
import { getTotalPrice } from './cart/selectors'

class Cart extends React.Component {
  render() {
    const { items, totalPrice } = this.props
    
    return (
      <div>
        <h3>Items</h3>
        {this.renderItems(items)}
        <p>Total price: {totalPrice}.</p>
      </div>
    )
  }
}

export default connect(state => ({
  items: state.getIn(['cart', 'items']),
  totalPrice: getTotalPrice(state.get('cart'))
})(Cart)