Today I Learned

A Hashrocket project

A React 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.

Looking for help? At Hashrocket, our JavaScript experts launch scalable, performant apps on the Web, Android and iOS. Contact us and find out how we can help you.