Is it safe to use ref.current as useEffect’s dependency when ref points to a DOM element?

When using React’s useEffect hook, it’s common to specify dependencies to ensure that the effect is only re-run when those dependencies change. However, there can be some confusion when it comes to using a ref as a dependency, especially when the ref points to a DOM element. In this article, we’ll explore whether it is safe to use ref.current as a dependency in useEffect when the ref points to a DOM element.

Before we dive into the details, let’s first understand what a ref is in React. A ref is an object that holds a mutable value and allows you to access the underlying DOM element or React component. It’s commonly used to interact with DOM elements directly or to store a reference to a component instance.

Now, let’s consider the scenario where you have a ref that points to a DOM element, and you want to use it as a dependency in useEffect. The question arises: is it safe to use ref.current as a dependency?

Using ref.current as a dependency

The short answer is yes, it is safe to use ref.current as a dependency in useEffect when the ref points to a DOM element. React guarantees that the ref.current value will always be up-to-date within the effect.

Here’s an example to illustrate this:

import React, { useEffect, useRef } from 'react';

function MyComponent() {
  const ref = useRef();

  useEffect(() => {
    // Access the DOM element using ref.current
    const element = ref.current;
    
    // Perform some logic with the element
    // ...

    // Cleanup function
    return () => {
      // Cleanup logic
      // ...
    };
  }, [ref.current]);

  return 
Hello, World!
;
}

In the above example, we have a component called MyComponent that renders a div element with a ref. Inside the useEffect hook, we access the DOM element using ref.current and perform some logic with it. We also provide [ref.current] as the dependency array, indicating that the effect should re-run whenever ref.current changes.

React ensures that the ref.current value is always up-to-date within the effect, so you can safely use it as a dependency. This means that if the ref.current value changes, the effect will be re-run, allowing you to handle any necessary logic or cleanup.

Alternative solution

While using ref.current as a dependency is safe, there is an alternative solution that you can consider. Instead of using ref.current as a dependency, you can use the ref itself as a dependency. This approach ensures that the effect is re-run whenever the ref changes, regardless of whether the ref.current value changes.

import React, { useEffect, useRef } from 'react';

function MyComponent() {
  const ref = useRef();

  useEffect(() => {
    // Access the DOM element using ref.current
    const element = ref.current;
    
    // Perform some logic with the element
    // ...

    // Cleanup function
    return () => {
      // Cleanup logic
      // ...
    };
  }, [ref]);

  return 
Hello, World!
;
}

In this alternative solution, we provide [ref] as the dependency array. This ensures that the effect is re-run whenever the ref itself changes, which includes changes to the ref.current value.

Conclusion

Using ref.current as a dependency in useEffect when the ref points to a DOM element is safe. React guarantees that the ref.current value will always be up-to-date within the effect. However, you can also consider using the ref itself as a dependency if you want the effect to re-run whenever the ref changes, regardless of whether the ref.current value changes.

Remember to choose the approach that best suits your specific use case and requirements. Happy coding!