a-component-is-just-a-bag-of-data.md

A Component Is Just A Bag Of Data

If you write enough React using JSX, it is easy to forget that you're not working with markup. Everything -- divs, h1s, 3rd party components, your components -- all get boiled down to JavaScript objects full of data.

Any given React component is really just a bag of data. Try doing a console.log to see. Here is an example from an earlier post.

const ParentWithClick = ({ children }) => {
  return (
    <React.Fragment>
      {React.Children.map(children || null, (child, i) => {
        console.log(child);
        return <child.type {...child.props} key={i} onClick={handleClick} />;
      })}
    </React.Fragment>
  );
};

const App = () => (
  <div>
    <ParentWithClick>
      <span>Click this span</span>
    </ParentWithClick>
  </div>
);

Looking in the console, we see the following output:

Object {type: "span", key: null, ref: null, props: Object, _owner: Object…}
 type: "span"
 key: null
 ref: null
 props: Object
  children: "Click this span"
 _owner: Object
 _store: Object

It contains information about the component itself and because of the tree structure of this data, you could potentially expand the props --> children sections several times for certain components.

See a live example here.