Create Ref using React.createRef without using constructor in React?

Question

Basically, I have used constructor in React for only 3 reasons -

1. To initialize state like -

class App extends React.Component {
    constructor(props) {
        super(props);
        this.state = { counter: 0 };
    }
}

but due to Babel's class-field support, I don't use it anymore

class App extends React.Component {
    state = { counter: 0 };
}

2. To bind functions like -

class App extends React.Component {
    constructor(props) {
        super(props);
        this.increment.bind(this);
    }

    increment() {

    }
}

but due to arrow functions, I don't do it anymore

class App extends React.Component {
    increment = () => {

    }
}

3. To use createRef like -

class App extends React.Component {
    constructor(props) {
        super(props);
        this.inputRef = React.createRef();
    }
}

So can I use React.createRef without using constructor in React?

Answer 1

You can declare it as an class field just like state.

class App extends React.Component {
  state = { counter: 0 };
  inputRef = React.createRef();
}

Babel will transpile it into something like the code below in stage-2 presets.

constructor(props) {
    super(props);

    this.state = { counter: 0 };
    this.inputRef = React.createRef();
  }

Answer 2

Yes, you can. For example:

const MyComponent = () => {
  const inputRef = React.createRef();

  return (
    <input ref={inputRef} />
  );
}

The only thing you cannot do, is pass the ref attribute to a functional component:

render() {
  // This won't work.
  return <MyFunctionalComponent ref={this.inputRef} />
}

---

More info from the official docs, here:

You can, however, use the ref attribute inside a function component as long as you refer to a DOM element or a class component:

Answer 3

you can create a ref with ref callbacks without using constructor. <input ref={(element) => { this.inputRef = element; }} /> is what you need.

Answer 4

On class components write like below:

import React, { Component, createRef } from 'react';

class App extends Component {
  inputRef = createRef();

  render() {
    return (
      <div ref={this.inputRef}~~~
    );
  }
}

On functional components write like below:

import React, { useRef } from 'react';

const App = () => {
  const inputRef = useRef(null);

  return (
    <div ref={inputRef}~~~
  );
};

Definitely, the referenced element is mutable object but it should persist for the full lifetime of the component. it is not my opinion, this words are for ReactJS docs.