api.js

const axios = require('axios');

export const getItems = () => axios.get('/api/items');

ItemsList.js

const React = require('react');
const getItems = require('./api').getItems;

class ItemsList extends React.Component {
  constructor(props) {
    super(props);
    
    this.state = {
      items: []
    }
  }
  
  componentDidMount() {
    getItems().then(response => {
      const items = response.data;
      this.setState({ items });
    });
  }
  
  componentWillUnmount() {
    // cancel request
  }
  
  render() {
    // render items
  }
}