React Useeffect Hook When Only One Of The Effects Deps Changes But Not The Others

If you are working on a React project and find yourself in a situation where you need to use the useEffect hook but want it to only run when one specific dependency changes, this article is for you. React's useEffect hook is a powerful tool for managing side effects in functional components. However, it can sometimes be tricky to configure it to only trigger when certain dependencies change, especially if you have multiple dependencies and only want the effect to run when one of them changes while ignoring changes in the others.

Imagine a scenario where you have a component that depends on multiple variables, but you only want the useEffect hook to run when one of those variables changes, and not when the others change. How can you achieve this?

One solution is to create a custom hook that leverages the useRef hook to keep track of the previous values of the dependencies and compare them to the current values. This way, you can conditionally run the effect based on whether the specific dependency you are interested in has changed.

Here's an example of how you can implement this custom hook:

Jsx

import { useEffect, useRef } from 'react';

function useStateEffectWithSpecificDependency(effect, deps, specificDep) {
  const prevSpecificDep = useRef(specificDep);

  useEffect(() =&gt; {
    if (prevSpecificDep.current !== specificDep) {
      effect();
    }
    prevSpecificDep.current = specificDep;
  }, deps);
}

In this custom hook, `useStateEffectWithSpecificDependency`, we store the previous value of the specific dependency using the useRef hook. Inside the useEffect function, we compare the previous value with the current value of the specific dependency. If they are different, we call the provided effect function. Finally, we update the previous value to reflect the current value of the specific dependency.

You can use this custom hook in your component like this:

Jsx

function MyComponent({ specificValue }) {
  useEffect(() =&gt; {
    // Your effect logic here
    console.log('Effect ran because specificValue changed');
  }, [specificValue]);

  useStateEffectWithSpecificDependency(() =&gt; {
    // Your specific effect logic here
    console.log('Specific effect ran because specificValue changed');
  }, [specificValue], specificValue);

  return <div>{specificValue}</div>;
}

In the example above, the first useEffect hook will run whenever `specificValue` changes, while the custom hook `useStateEffectWithSpecificDependency` ensures that the specific effect only runs when the `specificValue` changes and not when any other dependencies change.

By using this custom hook, you can have more control over when your effects should run based on specific dependency changes, providing a more granular approach to managing side effects in your React components. Utilize this technique to optimize the performance and behavior of your React applications efficiently.

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