import React, { Component } from 'react'
...

class UserCard extends Component {

  constructor(props) {
    super(props);

    this.state = {
      name: 'Akexorcist'
    }

    this.onButtonClick = this.onButtonClick.bind(this);
  }

  onButtonClick() {
    ...
  }

  ...
}

export default UserCard