React and autofocus

By  on  

While I love ReactJS, I can say that I sometimes find interactions that were easy during the pre-ReactJS are annoyingly difficult or at least "indirect".  One example is properly ensuring that a given <input> element gets focused when a button in a different component is clicked; in the old days, it was three lines of code, but with React it can be more.

Let's have a look at a few strategies for properly focusing on <input> elements with ReactJS.

autofocus

The autofocus attribute is honored in ReactJS but only when the <input> element is re-rendered with React:

<input type="text" autofocus="true" />

autofocus is easy to use but only works when the <input> is initially rendered; since React intelligently only re-renders elements that have changed, the autofocus attribute isn't reliable in all cases.

componentDidUpdate with ref

Since we can't rely solely on the autofocus attribute, we can use componentDidUpdate to complete the focus:

class Expressions extends Component {

  _input: ?HTMLInputElement;

  // ....

  componentDidUpdate(prevProps, prevState) {
    this._input.focus();
  }

  render() {
      return (
        <div className={this.state.focused ? "focused": ""}>
            <input
              autofocus="true"
              ref={c => (this._input = c)}
            />
        </div>
      );
    }
  }
}

componentDidUpdate fires after the component is updated, so any change to the parent component would trigger this method and your <input> would receive focus.  In my cases, I usually toggle a className on the parent element to signal the element is active and thus the componentDidUpdate will trigger.

My perspective of inter-widget interaction has been formed by the days of Dojo's dijit UI framework where each widget usually had a reference to every child widget; with ReactJS the practice is (hopefully) avoiding refs and using state, which is logical but there's still that piece of me that longs for a simple reference, which is why the second strategy makes sense to me.

Recent Features

  • By
    Page Visibility API

    One event that's always been lacking within the document is a signal for when the user is looking at a given tab, or another tab. When does the user switch off our site to look at something else? When do they come back?

  • By
    From Webcam to Animated GIF: the Secret Behind chat.meatspac.es!

    My team mate Edna Piranha is not only an awesome hacker; she's also a fantastic philosopher! Communication and online interactions is a subject that has kept her mind busy for a long time, and it has also resulted in a bunch of interesting experimental projects...

Incredible Demos

  • By
    Create a Context Menu with Dojo and Dijit

    Context menus, used in the right type of web application, can be invaluable.  They provide shortcut methods to different functionality within the application and, with just a right click, they are readily available.  Dojo's Dijit frameworks provides an easy way to create stylish, flexible context...

  • By
    Smooth Scrolling with MooTools Fx.SmoothScroll

    I get quite a few support requests for my previous MooTools SmoothScroll article and the issue usually boils down to the fact that SmoothScroll has become Fx.SmoothScroll. Here's a simple usage of Fx.SmoothScroll. The HTML The only HTML requirement for Fx.SmoothScroll is that all named...

Discussion

  1. Hi David.

    Great article — as always. It is just worth to update a syntax of reference to the now one (updated in 16.3) using

    React.createRef()

    .

    https://reactjs.org/docs/react-api.html#reactcreateref

    Thanks

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!