ClassButton.js

import React from "react";

class Button extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      disabled: false
    };
    this.handleClick = this.handleClick.bind(this);
  }

  handleClick = () => {
    this.setState({
      disabled: true
    });
  };

  render() {
    return (
      <button onClick={this.handleClick} disabled={this.state.disabled}>
        {this.props.children}
      </button>
    );
  }
}

export default Button;