component.js

import React from 'react';

class Component extends React.Component {
  constructor() {
    super();
    this.state = {
      data: [],
    };
  }

  handleRequest = () => {
    fetch('/api')
      .then(res => res.json)
      .then(data => {
        this.setState({
          data
        });
      });
  }
  render() {
    console.log(this.state.data);
    return (
      <div>
        <button onClick={this.handleRequest}>
        Get Data
        </button>
      </div>
    );
  }
}

export default Component;