2019-11-07
2580
#react
Andrew James
9113
Nov 7, 2019 ⋅ 9 min read

Building a responsive camera component with React Hooks

Andrew James Frontend Engineer @ Coinbase

Recent posts:

i tried kiro and here is what i learned

I tried out Kiro: Here’s what I learned

Check out Kiro, AWS’s AI-powered IDE, see what makes it different from other AI coding tools, and explore whether it lives up to the hype.

Elijah Asaolu
Aug 28, 2025 ⋅ 5 min read
Go Design Pattern Article Image With Logo

Why Go design patterns still matter

Here’s how three design patterns solved our Go microservices scaling problems without sacrificing simplicity.

Peter Aideloje
Aug 28, 2025 ⋅ 2 min read
how to protect your ai agent from prompt injection attacks

How to protect your AI agent from prompt injection attacks

Explore six principled design patterns (with real-world examples) to help you protect your LLM agents from prompt injection attacks.

Rosario De Chiara
Aug 27, 2025 ⋅ 5 min read
Don’t Let AI Erase The Next Generation Of Dev Leaders

Don’t let AI erase the next generation of dev leaders

As AI tools take over more routine coding work, some companies are cutting early-career dev roles — a short-sighted move that could quietly erode the next generation of tech leaders if we aren’t careful.

Jack Herrington
Aug 26, 2025 ⋅ 6 min read
View all posts

7 Replies to "Building a responsive camera component with React Hooks"

  1. This was really helpful in learning. I noticed that the main camera component is capitalized, but the supporting functions like useUserMedia are not. As a best practice where should those supporting functions live? Guessing not in a folder like Camera would inside of a Components folder.

  2. Super helpful, thank you for posting this.

    However your useUserMedia wasn’t working properly for me, so I refactored it like this:

    import { useState, useEffect } from “react”;

    export function useUserMedia(requestedMedia) {
    const [mediaStream, setMediaStream] = useState(null);

    useEffect(() => {
    // Creating reference at the top of useEffect’s scope for cleanup later
    let streamRef = null;

    async function enableStream() {
    try {
    // Using ref instead of a new const variable
    streamRef = await navigator.mediaDevices.getUserMedia(requestedMedia);
    setMediaStream(streamRef);
    } catch(err) {
    // Removed for brevity
    }
    }

    if (!mediaStream) {
    enableStream();
    }

    // Removed else block
    return function cleanup() {
    // Now the ref can be used to stop all media tracks
    streamRef.getTracks().forEach(track => {
    track.stop();
    });
    }

    // Removed dependency array
    }, []);

    return mediaStream;

    Now when the component unmounts, the camera stops recording.

    1. I had a similar issue, but in dev mode the cleanup function was running before the getUseMedia promise resolved, so the streamRef was null when cleanup ran and the MediaStream wasn’t closed. This meant that when I clicked “Take a picture”, the webcam stayed on.

      The way I got around this was by using a streamRefArray outside of the useEffect and pushing each new stream into that instead of reassigning the the streamRef variable. Then, on cleanup, I’d loop through the streamRefArray MediaStreams and stop all their tracks. This seemed to do the trick.

      import { useState, useEffect } from “react”

      export function useUserMedia(requestedMedia: MediaStreamConstraints) {
      const [mediaStream, setMediaStream] = useState(null)
      let streamRefArray: MediaStream[] = []

      useEffect(() => {
      async function enableStream() {
      try {
      const stream = await navigator.mediaDevices.getUserMedia(requestedMedia)
      // Push media stream to reference array
      // to stop track in later cleanup
      streamRefArray.push(stream)
      setMediaStream(stream)
      } catch (err) {
      console.error(err)
      }
      }

      if (!mediaStream) {
      enableStream()
      }

      return function cleanup() {
      // Loop through array of media streams
      streamRefArray.forEach((stream) => {
      stream?.getTracks().forEach((track) => {
      console.log(track)
      track.stop()
      })
      streamRefArray = []
      })
      }
      }, [])

      return mediaStream
      }

  3. Hi Andrew,
    Can you please shed some light on how to resize the container for mobile devices, as for the mobile devices i need height > width.
    Thanks in Advance.

Leave a Reply