How to Get an element by ID in React

# Table of Contents

1. Get an element by ID using a ref in React
2. Get an element by ID using document.getElementById
3. Get an element by ID when an Event occurs in React
4. [Solved] document.getElementById() returns NULL in React

# Get an element by ID using a ref in React

To get an element by ID using a ref:

1. Set the ref prop on the element.
2. Use the current property to access the element in the useEffect hook.

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import {useRef, useEffect} from 'react';

export default function App() {
  const ref = useRef(null);

  useEffect(() => {
    const element = ref.current;
    console.log(element);
    console.log(element.id);
  }, []);

  return (
    <div>
      <h2 ref={ref} id="box">
        bobbyhadz.com
      </h2>
    </div>
  );
}

The equivalent of getting an element by ID in React is to use a ref.

The useRef() hook can be passed an initial value as an argument.

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const ref = useRef(null);

The hook returns a mutable ref object whose .current property is initialized to the passed argument.

We set the ref prop on the element we need to access.

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<h2 ref={ref} id="box">
  bobbyhadz.com
</h2>

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useEffect(() => {
  const element = ref.current;
  console.log(element);
  console.log(element.id);
}, []);

When we pass a ref prop to an element, e.g. <div ref={myRef} />, React sets the .current property of the ref object to the corresponding DOM node.

We passed an empty dependencies array to the useEffect hook, so it's only going to run when the component mounts.

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useEffect(() => {
  const element = ref.current;
  console.log(element);
  console.log(element.id);
}, []);

We used the useEffect hook because we want to make sure the ref has been set on the element and the element has been rendered to the DOM.

The useRef hook is the React.js equivalent of the document.getElementById method in JavaScript.

However, you are still able to use the method in React.js as well.

If you don't have access to the element you are trying to select in your component and can't simply set the ref prop on it, use the document.getElementById() method.

I've also written a tutorial on how to get the ID of an element on click.

# Get an element by ID using document.getElementById

This is a two-step process:

1. Use the useEffect hook to invoke a function once the component mounts.
2. Use the document.getElementById() method in the useEffect hook.

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import {useEffect} from 'react';

export default function App() {
  useEffect(() => {
    const element = document.getElementById('box');
    console.log(element);
    console.log(element.id);
  }, []);

  return (
    <div>
      <h2 id="box">bobbyhadz.com</h2>
    </div>
  );
}

The document.getElementById() method takes an ID as a parameter and returns the element with the given ID.

You have to call the document.getElementById() method in the useEffect hook or when an event occurs.

A commonly used convention in React is to only use the document.getElementById method when you don't have access to the DOM element and can't set a ref on it.

# Get an element by ID when an Event occurs in React

Here is an example that gets an element by ID when an event occurs.

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import {useRef} from 'react';

export default function App() {
  const ref = useRef(null);

  const handleClick = () => {
    // 👇️ use document.getElementById()
    const element = document.getElementById('box');
    console.log(element);

    // 👇️ (better) use a ref
    const element2 = ref.current;
    console.log(element2);
  };

  return (
    <div>
      <h2 ref={ref} id="box">
        bobbyhadz.com
      </h2>

      <button onClick={handleClick}>Click</button>
    </div>
  );
}

Selecting an element by ID or using a ref is also possible in an event handler function.

The useEffect hook runs after the DOM elements in the component have been rendered to the DOM, so if an element with the provided id exists, it will be selected.

You can also use the document.querySelector method in React.

# [Solved]: document.getElementById() returns NULL in React

The document.getElementById() method returns null in React when we call the method before the element with the provided ID has been rendered to the DOM or if an element with the ID doesn't exist.

To get around this, call the getElementById() method in the useEffect hook.

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import {useEffect} from 'react';

export default function App() {
  useEffect(() => {
    // 👇️ call method in useEffect hook
    const el = document.getElementById('container');
    console.log(el);
  }, []);

  return (
    <div>
      <div id="container">
        <h2>bobbyhadz.com</h2>
      </div>
    </div>
  );
}

The 2 most common reasons for the document.getElementById() method to return null in React are:

1. Trying to select an element that hasn't been rendered to the DOM yet.
2. Supplying an ID that doesn't exist in the DOM.

# Use document.getElementById in the useEffect hook

You can use the document.getElementById method in the useEffect hook because the hook runs after the component has been mounted.

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useEffect(() => {
  // 👇️ call method in useEffect hook
  const el = document.getElementById('container');
  console.log(el);
}, []);

We passed an empty dependencies array to the useEffect hook, so it's only going to run on the initial render.

You can also call the document.getElementById() method in an event handler function, e.g. in an onClick handler because the element will be present in the DOM when the event is triggered.

# Using a ref instead of document.getElementById()

Note that if you have access to the DOM element in your component, you can use a ref.

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import {useRef, useEffect} from 'react';

export default function App() {
  const ref = useRef(null);

  useEffect(() => {
    const el = ref.current;
    console.log(el);
  }, []);

  return (
    <div>
      <div ref={ref}>
        <h2>bobbyhadz.com</h2>
      </div>
    </div>
  );
}

The useRef() hook can be passed an initial value as an argument. The hook returns a mutable ref object whose .current property is initialized to the passed argument.

Copied!
useEffect(() => {
  const el = ref.current;
  console.log(el);
}, []);

When we pass a ref prop to an element, e.g. <div ref={myRef} />, React sets the .current property of the ref object to the corresponding DOM node.

We used the useEffect hook because we want to make sure the ref has been set on the element and the element has been rendered to the DOM.

Using refs should be your preferred approach when you have access to the element in your component, otherwise, you can use the document.getElementById method.