Using useState with an object: how to update
New Course Coming Soon:
Get Really Good at Git
When a state variable defined with useState is an object with properties you add / update, it’s somewhat confusing how to update it.
You can’t just update the object, or the component won’t rerender.
A pattern I found involves creating a temporary object with one property, and use object destructuring to create a new object from the existing 2 objects:
const [quizAnswers, setQuizAnswers] = useState({})
...
const updatedValue = {}
updatedValue[quizEntryIndex] = answerIndex
setQuizAnswers({
...quizAnswers,
...updatedValue
})
The same technique can be used to remove a property:
const copyOfObject = { ...quizAnswers }
delete copyOfObject['propertyToRemove']
setQuizAnswers({
...copyOfObject
})
Are you intimidated by Git? Can’t figure out merge vs
rebase? Are you afraid of screwing up something any time
you have to do something in Git? Do you rely on ChatGPT
or random people’s answer on StackOverflow to fix your
problems? Your coworkers are tired of explaining Git to
you all the time? Git is something we all need to use,
but few of us really master it. I created this course to
improve your Git (and GitHub) knowledge at a radical
level. A course that helps you feel less frustrated with
Git. Launching Summer 2024. Join the waiting list!
→ Get my
React Beginner's Handbook
→ Read my full
React Tutorial
on The Valley of Code
Here is how can I help you:
- COURSES where I teach everything I know
- THE VALLEY OF CODE your web development manual
- BOOTCAMP 2024 cohort in progress, next edition in 2025
- BOOKS 16 coding ebooks you can download for free on JS Python C PHP and lots more
- SOLO LAB everything I know about running a lifestyle business as a solopreneur
- Interesting links collection
- Follow me on X