Binding methods in React supplies the appropriate context so that a function can be passed around.

React - .bind()

class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
    }
    this.searchDB = this.searchDB.bind(this); 
    this.handleClick = this.handleClick.bind(this); // This was the missing critical line
  }
  
  handleClick (type, param) {
    if (type === "Search") {
      this.searchDB(param);
    }
    else console.log('No type managed --> ', type);
  }

  searchDB (query) {
    console.log(`The search query is --> `, query);
  }
  render () {
		...
	}
}