You have probably been passing props
from parent to child components, and you have questioned yourself: "Hmm... but what if I want to pass props from child to a parent component? I mean... the other way round?", right? π€ I have also questioned myself that, but there are solutions actually.
We will go through them.
What is the typical flow of props?
The typical flow of props is from parent to child. Basically, let's say you have a Parent
component which looks like this:
The child component we have below uses a Button
component from the very much beloved shadcn/ui component library. The Button
component has a children
prop, which is passed from the Parent
component.
Above, we are passing a children
prop from the Parent
component to the Child
component. All good so far, right?
What if we want to pass props from child to parent?
Now, this is where things get a bit tricky, espcially if it is your first time implementing such logic. The tricky part about it is probably not how to go about doing it, but more how to visualize it. Either way, I have been there, and my experience will hopefully help you out π
Because learning is best done by doing, let's bring the example from earlier, and modify it a bit to see how we can pass props from child to parent. The goal of this example is to show how we can modify the state of the Parent
component by passing data from the Child
component.
And here is what we do from the Child
component:
Making it simpler to understand in written form, what we are trying to accomplish with the two components is that we initialise the state in the Parent
component, and then pass the variables down to the Child
component, and the respective function to update the value of the state in the Parent
component. In this case, suppose the value of the state is first set to false
. When we click on the button from the Child
component, it will take that value, and change it to the opposite of false
(!
in the value negates it) when the function gets called on the click event.
A common pitfall while passing data from child to parent
Passing data from the child component to the parent does have its quirks. One of the most common pitfalls is forgetting to pass the callback function as a prop to the child component, but that also means that you are passing more logic that you you need to pass. This can lead to more annoying, and harder to debug bugs.
One way to prevent this is to use the useCallback
hook, which makes sure that the function you pass as a callback to the child component remains stable across renders, preventing unnecessary re-renders and improving performance. What happens with useCallback
is that you pass a function as a prop to the child component, and the child component will have access to the function, and can call it when needed. Let's see how we can do this.
Now let's show how it looks like in the Child
component:
Isn't this cleaner than passing the function, and then updating it from the child, and then passing again to the parent? Cleaner, and easier to implement, too, right? π€©
Thank you for reading!
Even though there are surely more, and potentially even cleaner, better-looking ways of passing data from child to parent in React, I hope that after reading my article, you will find it easier to understand the flow of how data passes from child to parent, and how to go about implementing that with two different ways. Who knows, maybe you will find a more creative way of doing it yourself? π If so, it would be greatly appreciated to explain your ideas in the comments!
About the Author
I'm a software developer, and technical writer based in Portugal. I'm passionate about software engineering π¨βπ» and I love to explore new tools in my day-to-day, and find interesting, and creative solutions to common business, and techincal problems. You can find me on GitHub. If you have any questions or feedback, feel free to reach out! π
Top comments (10)
Hi Bruno, thank you for the great post. I am doing something similar, and finding myself lost in the syntax. I have been able in the past to pass values as props from Parent to Child components, as well as implement your callback solution.
I was wandering what would be the correct syntax to (lets say by making it analogous to your example):
I tried:
const Child = (props, {handleOpen }) => {}
...but in this case handleOpen is not recognised as a function.
Keep up the good work and thnx in advance for your time.
Regards
Hi Alban, thank you for positive feedback and for reading this post. I hope it was helpful to you somehow.
As for the syntax, there are two main ways you can get access to the
handleOpen
function in the child component:pass only the main
props
to the parameterdestructure the
handleOpen
and use it in the child componentWhy you can't use the syntax you tried is because React only gives you the
props
object, so you can only use one of the two, but neverprops
andhandleOpen
in the same function definition (adding both as arguments basically).It is a bit of a confusing approach probably, but basically you either use one approach or the other if you want to access the
handleOpen
in the child component.The right syntax is:
const Child = ({handleOpen}) => { }
Props are always passed as a single object, so destructuring should happen inside the first parameter itself.
Right, and ambiguous at the same time. Like I explained in my response, you can use either of the two approaches. None of them is "right" or wrong. If you want to pass only a specific prop to the child component, then use the second approach and specify the prop with the destructuring, otherwise use the first approach if you want to pass a collection of props or pass them to other components. Be careful with saying something is right or wrong when there are multiple approaches available.
I like how you also explain the merrits of using useCallback in this case! Btw if the child component doesnt depend on
isOpen
you can prevent it from rendering by removing the isOpen dependency in the callback:Thank you for the positive feedback, and for the suggestion, Rense! Much appreciated, and good point for sure :D
π Nice.
It would be nicer using
useContext()
Thank you for your positive feedback, and the interesting suggestion! That definitely deserves an article of itβs own.
great postοΌ
Thank you so much for the positive feedback!π
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