import React, { Component } from 'react';

class SearchBar extends Component {
  render() {
    return <input />;
  }
}

export default SearchBar;

import React, { Component } from 'react';

class SearchBar extends Component {
  constructor(props) {
    super(props);

    this.state = {
      term: ''
    };
  }

  render() {
    return (
      <div>
        <input onChange={event => this.setState({ term: event.target.value })} />
        Value of the input: {this.state.term}
      </div>
    );
  }
}

export default SearchBar;

Introduce state, use Arrow function instead of onInputChange.