20 Most Asked Custom Hooks In React for Interviews

Custom hooks improve the overall reusability in the react application and reduce down the boilerplate code. Understanding custom hooks are so important that Nowadays Custom Hooks in React are one of the most asked React Interviews questions.

Any number of custom hooks can be make as per the requirement, so to help you out we have captured the 20 most asked Custom Hooks in React with code implementation for quick revision before your frontend interview

Table of content

1. useFetch() Hook
2. useToggle() Hook
3. useTheme() Hook
4. usePrefersColorScheme() Hook
5. useLocalStorage() Hook
6. useSessionStorage() Hook
7. useDebounce() Hook
8. useThrottle() Hook
9. useIntersectionObserver() Hook
10. usePrevious() Hook
11. useOnClickOutside() Hook
12. useCopyToClipboard() Hook
13. useInfiniteScroll() Hook
14. useDocumentTitle() Hook
15. usePolling() Hook
16. useOnlineStatus() Hook
17. useScrollPosition() Hook
18. useKeyPress() Hook
19. useMediaQuery() Hook
20. useWindowSize() Hook

1. useFetch() Hook

The useFetch hook in react is used for making HTTP requests in React components, and handle the loading, error states better.

import { useState, useEffect } from 'react';

const useFetch = (url) => {
    const [data, setData] = useState(null);
    const [loading, setLoading] = useState(true);

    useEffect(() => {
        const fetchData = async () => {
            const response = await fetch(url);
            const result = await response.json();
            setData(result);
            setLoading(false);
        };

        fetchData();
    }, [url]);

    return { data, loading };
};

export default useFetch;

Detailed useFetch Hook Guide →

2. useToggle() Hook

The useToggle hook is used to toggle between two states.

import { useState } from 'react';

const useToggle = (initialState = false) => {
    const [state, setState] = useState(initialState);

    const toggle = () => {
        setState(!state);
    };

    return [state, toggle];
};

export default useToggle;

Detailed useToggle Hook Guide →

3. useTheme() Hook

The useTheme hook is used for managing themes in a React application.

import { useState } from 'react';

const useTheme = () => {
    const [theme, setTheme] = useState('light');

    const toggleTheme = () => {
        setTheme(theme === 'light' ? 'dark' : 'light');
    };

    return [theme, toggleTheme];
};

export default useTheme;

Detailed useTheme Hook Guide →

4. usePrefersColorScheme() Hook

The usePrefersColorScheme hook is used to detect the user's preferred color scheme.

import { useState, useEffect } from 'react';

const usePrefersColorScheme = () => {
    const [colorScheme, setColorScheme] = useState('light');

    useEffect(() => {
        const mediaQuery = window.matchMedia('(prefers-color-scheme: dark)');
        setColorScheme(mediaQuery.matches ? 'dark' : 'light');
    }, []);

    return colorScheme;
};

export default usePrefersColorScheme;

5. useLocalStorage() Hook

The useLocalStorage hook is used to persist state in local storage.

import { useState } from 'react';

const useLocalStorage = (key, initialValue) => {
    const [value, setValue] = useState(() => {
        const storedValue = localStorage.getItem(key);
        return storedValue ? JSON.parse(storedValue) : initialValue;
    });

    const setStoredValue = (newValue) => {
        setValue(newValue);
        localStorage.setItem(key, JSON.stringify(newValue));
    };

    return [value, setStoredValue];
};

export default useLocalStorage;

Detailed useLocalStorage Hook Guide →

6. useSessionStorage() Hook

The useSessionStorage hook is similar to useLocalStorage but interacts with session storage instead.

// Implementation of useSessionStorage
const useSessionStorage = (key, initialValue) => {
  const [storedValue, setStoredValue] = useState(() => {
    const item = window.sessionStorage.getItem(key);
    return item ? JSON.parse(item) : initialValue;
  });

  const setValue = value => {
    setStoredValue(value);
    window.sessionStorage.setItem(key, JSON.stringify(value));
  };

  return [storedValue, setValue];
};

Detailed useSessionStorage Hook Guide →

7. useDebounce() Hook

The useDebounce hook delays the execution of a function until a specified time has elapsed since the last invocation.

// Implementation of useDebounce
const useDebounce = (value, delay) => {
  const [debouncedValue, setDebouncedValue] = useState(value);

  useEffect(() => {
    const handler = setTimeout(() => {
      setDebouncedValue(value);
    }, delay);

    return () => {
      clearTimeout(handler);
    };
  }, [value, delay]);

  return debouncedValue;
};

Detailed useDebounce Hook Guide →

8. useThrottle() Hook

The useThrottle hook limits the rate at which a function is executed.

// Implementation of useThrottle
const useThrottle = (value, delay) => {
  const [throttledValue, setThrottledValue] = useState(value);
  const lastExecTime = useRef(0);

  useEffect(() => {
    const now = Date.now();
    if (now - lastExecTime.current > delay) {
      setThrottledValue(value);
      lastExecTime.current = now;
    }
  }, [value, delay]);

  return throttledValue;
};

Detailed useThrottle Hook Guide →

9. useIntersectionObserver() Hook

Custom hook to observe when an element enters or exits the viewport.

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

const useIntersectionObserver = (target, options) => {
    const [isVisible, setIsVisible] = useState(false);
    const observer = useRef(new IntersectionObserver(
        ([entry]) => setIsVisible(entry.isIntersecting),
        options
    ));

    useEffect(() => {
        observer.current.observe(target);
        return () => observer.current.disconnect();
    }, [target]);

    return isVisible;
};

export default useIntersectionObserver;

Detailed useIntersectionObserver Hook Guide →

10. usePrevious() Hook

Custom hook to store the previous value of a state variable.

import { useEffect, useRef } from 'react';

const usePrevious = (value) => {
    const ref = useRef();
    useEffect(() => {
        ref.current = value;
    });
    return ref.current;
};

export default usePrevious;

Detailed usePrevious Hook Guide →

11. useOnClickOutside() Hook

The useOnClickOutside hook is used to detect clicks that occur outside a specified element. This is commonly used for implementing dropdowns, modals, or any component that needs to close when a user clicks outside of it.

import { useEffect } from 'react';

const useOnClickOutside = (ref, handler) => {
  useEffect(() => {
    const listener = (event) => {
      if (!ref.current || ref.current.contains(event.target)) {
        return;
      }
      handler(event);
    };
    document.addEventListener('mousedown', listener);
    return () => {
      document.removeEventListener('mousedown', listener);
    };
  }, [ref, handler]);
};

// Usage
// const ref = useRef();
// useOnClickOutside(ref, () => {
//   // Close the dropdown or modal
// });

Detailed useOnClickOutside Hook Guide →

12. useCopyToClipboard() Hook

The useCopyToClipboard hook is used for copying text to the clipboard. It provides a convenient way to implement copy functionality in your React components.

const useCopyToClipboard = () => {
  const copyToClipboard = (text) => {
    navigator.clipboard.writeText(text)
      .then(() => {
        console.log('Text copied to clipboard');
      })
      .catch((error) => {
        console.error('Failed to copy text to clipboard:', error);
      });
  };

  return { copyToClipboard };
};

// Usage
// const { copyToClipboard } = useCopyToClipboard();
// copyToClipboard('Text to be copied');

Detailed useCopyToClipboard Hook Guide →

13. useInfiniteScroll() Hook

The useInfiniteScroll hook allows you to handle the large list where data is populated (locally or from server using API call) dynamically while user scrolls and hit the bottom of the page (or Intersection point).

IntersectionObserver API can be used to implement this custom hook and This react hook can be useful for building application involving large amount of data to showcase in a lazy loaded fashion. Example - Catalog page of an e-commerce application.

const useInfiniteScroll = (callback) => {
    const observer = new IntersectionObserver((entries) => {
        if (entries[0].isIntersecting) {
            callback();
        }
    });

    useEffect(() => {
        observer.observe(document.getElementById('infinite-scroll-trigger'));

        return () => {
            observer.disconnect();
        };
    }, []);
};

Detailed useInfiniteScroll Hook Guide →

14. useDocumentTitle() Hook

The useDocumentTitle hook allows you to dynamically set the document title based on the state of your component. This can be useful for updating the title of your web application based on the content being displayed.

import { useEffect } from 'react';

const useDocumentTitle = (title) => {
  useEffect(() => {
    document.title = title;
  }, [title]);
};

// Usage
// useDocumentTitle('Page Title');

Detailed useDocumentTitle Hook Guide →

15. usePolling() Hook

usePolling custom hook allows you to fetch data from an API endpoint at regular intervals. This is a useful custom hook to reuse the polling logic as part of the custom hook.

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

const usePolling = (url, interval) => {
    const [data, setData] = useState(null);

    const fetchData = async () => {
        try {
            const response = await fetch(url);
            const jsonData = await response.json();
            setData(jsonData);
        } catch (error) {
            console.error('Error fetching data:', error);
        }
    };

    useEffect(() => {
        fetchData();

        const pollingId = setInterval(() => {
            fetchData();
        }, interval);

        return () => {
            clearInterval(pollingId);
        };
    }, [url, interval]);

    return data;
};

export default usePolling;

Detailed usePolling Hook Guide →

16. useOnlineStatus() Hook

The useOnlineStatus custom hook is used to track the online status of the user's browser. This can be useful for showing a message when the user is offline or for handling network-related features.

import { useState, useEffect } from 'react';

const useOnlineStatus = () => {
    const [isOnline, setIsOnline] = useState(navigator.onLine);

    useEffect(() => {
        const handleOnline = () => setIsOnline(true);
        const handleOffline = () => setIsOnline(false);

        window.addEventListener('online', handleOnline);
        window.addEventListener('offline', handleOffline);

        return () => {
            window.removeEventListener('online', handleOnline);
            window.removeEventListener('offline', handleOffline);
        };
    }, []);

    return isOnline;
};

export default useOnlineStatus;

Detailed useOnlineStatus Hook Guide →

17. useScrollPosition() Hook

The useScrollPosition custom hook is used to track the scroll position of the page. This can be handy for implementing effects based on scroll position, such as sticky headers or lazy loading content.

import { useState, useEffect } from 'react';

const useScrollPosition = () => {
    const [scrollPosition, setScrollPosition] = useState(window.scrollY);

    useEffect(() => {
        const handleScroll = () => {
            setScrollPosition(window.scrollY);
        };

        window.addEventListener('scroll', handleScroll);

        return () => {
            window.removeEventListener('scroll', handleScroll);
        };
    }, []);

    return scrollPosition;
};

export default useScrollPosition;

Detailed useScrollPosition Hook Guide →

18. useKeyPress() Hook

The useKeyPress custom hook is used to detect when a specific key is pressed. This can be used for implementing keyboard shortcuts or handling user input based on key presses.

import { useState, useEffect } from 'react';

const useKeyPress = (targetKey) => {
    const [keyPressed, setKeyPressed] = useState(false);

    const downHandler = ({ key }) => {
        if (key === targetKey) {
            setKeyPressed(true);
        }
    };

    const upHandler = ({ key }) => {
        if (key === targetKey) {
            setKeyPressed(false);
        }
    };

    useEffect(() => {
        window.addEventListener('keydown', downHandler);
        window.addEventListener('keyup', upHandler);

        return () => {
            window.removeEventListener('keydown', downHandler);
            window.removeEventListener('keyup', upHandler);
        };
    }, [targetKey]);

    return keyPressed;
};

export default useKeyPress;

Detailed useKeyPress Hook Guide →

19. useMediaQuery() Hook

The useMediaQuery custom hook is used to track the match of a CSS media query. This can be useful for implementing responsive designs and adapting components based on screen size or device type.

import { useState, useEffect } from 'react';

const useMediaQuery = (query) => {
    const [matches, setMatches] = useState(false);

    useEffect(() => {
        const mediaQuery = window.matchMedia(query);
        setMatches(mediaQuery.matches);

        const handler = (event) => setMatches(event.matches);

        mediaQuery.addListener(handler);

        return () => {
            mediaQuery.removeListener(handler);
        };
    }, [query]);

    return matches;
};

export default useMediaQuery;

Detailed useMediaQuery Hook Guide →

20. useWindowSize() Hook

useWindowSize lets you reactively track the browser window dimensions, useful for responsive UIs, conditionally rendering layouts, or adapting components based on screen size.

import { useState, useEffect } from "react";

function useWindowSize() {
  const [windowSize, setWindowSize] = useState({
    width: window.innerWidth,
    height: window.innerHeight,
  });

  useEffect(() => {
    function handleResize() {
      setWindowSize({
        width: window.innerWidth,
        height: window.innerHeight,
      });
    }

    // Add event listener
    window.addEventListener("resize", handleResize);

    // Call handler immediately so state is up to date
    handleResize();

    // Clean up listener on unmount
    return () => window.removeEventListener("resize", handleResize);
  }, []);

  return windowSize;
}

Detailed useWindowSize Hook Guide →

Thats It !!

Thanks for going through all of these custom hooks in React. These hooks cover all  most important patterns to implement the custom hooks. Even if there is any other custom hook implementation comes in the interview, you will be able to implement any new custom hooks based on the knowledge of the above 20 custom hooks in react.

Happy Coding :)

Further Reading 🚀

1. 100+ Top React JS Interview Questions and Answers
2. Best Resources for React Interview Preparation