How to create the this.state object for a React component?

You'd do this in the constructor(), which is called before your React.js component is mounted.

It'd look like this:

constructor(props) {
  super(props)
  this.state = {
    loading: false,
    inputValue: ""
  }
}

This will make this.state accessible to your component on a local specific level. And you can make updates to it using the this.setState() method.

super(props) is called to ensure this.props is not undefined inside the constructor(), which could cause issues.

The constructor() should be positioned at the top of component:

class YourComponent extends React.Component {
  constructor(props) {
    super(props)
    this.state = {
      loading: false,
      inputValue: ""
    }
  }

  render() {
    return (
      <div>Page content</div>
    )
  }
}