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What is prop drilling and how to avoid it

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Prop Drilling is a concept in React that is sometimes unavoidable but, in most cases, should not be applied. In This article, I will discuss what it is and how to avoid it.

Table of Contents

Props in React

To understand the concept of Prop drilling, we first need to clarify what props are in React and how they are such a crucial aspect of Reacts success concerning unidirectional data flow.

If you're already familiar with the concept of props in React, skip to the next section in this article. But you also might learn something new, like I did, although you've been working with React for a while.

First and foremost, props are short for Properties. Props are used to communicate from one component to another. For example, a Parent Component can pass information to children by using the concept of props. To pass props, you have to add them to the JSX, just like you can do with HTML attributes.

You can pass some predefined props to your child components, like className. You can also pass any props you want to your children. To read the props, you can either destructure the individual props inside your functions parenthesis or access the whole props object. Props are almost like function parameters.

Here is a simple example of passing props down from a parent to a child component and reading it there:

// Parent Component

function ProductDetails() {
  return (
    <ProductHeader
      className="parent-component"
      productName="The best product ever"
    />
  );
}

// Child Component accessing the whole props object
function ProductHeader(props) {
  return (
    <div className={props.className}>
      <h1>{props.productName}</h1>
    </div>
  );
}

// Child Component destructuring the props object
function ProductHeader({ className, productName }) {
  return (
    <div className={className}>
      <h1>{productName}</h1>
    </div>
  );
}

Not only can you pass values via props down to your children, but you can also send whole components through that informational pipeline. The parent component can access the nested component via the children's prop by nesting a component inside another component.

That's called passing JSX as children and is a widespread concept when composing React apps. This gets important again when we talk about how to avoid prop drilling. Here's an example of it:

function ProductDetails() {
  return (
    <ProductHeader>
      <div>
        <h1>The best product ever</h1>
      </div>
    </ProductHeader>
  )
}

function ProductHeader({ children }) {
  return <div>{children}</div>
}

What is prop drilling?

Now that we understand props in React, let's talk about prop drilling and why it can become a problem.

We talk about prop drilling when we pass the same props several levels deep down the component tree. Often these props get passed through components that are not interested in them but need to help pass them down to a certain point where they are required.

Here's an example of that. Imagine you have a component tree like this:

<App>
  <Header />
  <MainContent>
    <ProductList>
      <ProductCard>
        <ProductDetailsModal>
          <ProductDetails>
            <ProductHeader />
            <ProductDescription />
            <ProductPrice />
          </ProductDetails>
        </ProductDetailsModal>
      </ProductCard>
    </ProductList>
  </MainContent>
  <Footer />
</App>

On the root level, you fetch the data of the products from your API and pass it down to the components that need it.

Imagine we want to display the name of product in the ProductHeader component. This means we need to pass the prop that withholds this information all the way through our component tree six levels down. On the way five components get this information, altough they aren't even interested in it.

const productName = 'The best product ever'

<App productName={productName}>
  <Header />
  <MainContent productName={productName}>
    <ProductList productName={productName}>
      <ProductCard productName={productName}>
        <ProductDetailsModal productName={productName}>
          <ProductDetails productName={productName}>
            <ProductHeader productName={productName} />
            <ProductDescription />
            <ProductPrice />
          </ProductDetails>
        </ProductDetailsModal>
      </ProductCard>
    </ProductList>
  </MainContent>
  <Footer />
</App>

Why is this a problem? This seems to be the recommended way to pass down information in React. For a few levels deep, making use of prop drilling is fine.

But it gets messy if you apply this technique several levels down the component tree. First of all, passing props down so deeply involves a lot of work. And second, if you make one change to these props, you have to update these changes everywhere, which makes it verbose and inconvenient.

Another big reason to avoid prop drilling is that debugging is harder. Imagine you notice that on the level where you do something with the data, you pass down so many levels, you get wrong values. So now you must trace the data through all the components and figure out where something went wrong.

Context is not the solution

When React Context was introduced, many developers believed this was the perfect solution for a) global state management in React and b) to avoid prop drilling.

Context lets a parent component provide data to the entire tree below. Here's an example of using context with the code from above:

const ProductContext = React.createContext()

function App() {
  const productName = 'The best product ever'

  return (
    <ProductContext.Provider value={productName}>
      <Header />
      <MainContent />
      <Footer />
    </ProductContext.Provider>
  )
}

function ProductHeader() {
  const productName = React.useContext(ProductContext)

  return <h1>{productName}</h1>
}

First we have to create a context object with React.createContext(). Then we wrap our whole Application with a Provider component that provides the data we want to pass down to the entire tree below.

At the point where we want to access the data, we use the useContext Hook to access the data. In this case it's ProductHeader, which, as we've seen in the example above, lies deeply nested inside the MainContent component.

This looks perfect, right? No need to pass props down several levels deep and we can access it easily, where we actually need it.

If you consider using context to avoid prop drilling, I must disappoint you. That's a bad idea. Just because you must pass some props several levels deep doesn't mean you should put that information into context.

It's really easy to overuse this concept. So the official recommendation by the React docs is to use context only for specific use cases and not just to avoid prop drilling.

One of these use cases is theming, for example. If you want to style your components differently, context is helpful to provide this information to the components that need it when a dark mode is applied, for example. You can check out the other recom use-cases for Context in the official React docs Opens in new tab.

Composition

So, what else can we do if context is not the perfect solution to avoid prop dilling? The answer is composition. Composition in React means how you arrange your component tree. Dan Abramov, one of the core team members for React, even wrote a tweet that being good at composing your React components is a top skill to learn in 2023  Opens in new tab.

Let's recap real quick. First, prop drilling in React can be verbose and inconvenient because debugging a prop passed down through many components can be hard to debug.

And If you pass some data through many layers of intermediate components that don't use that data (and only pass it further down), this often means that you forgot to extract some components along the way.

Extracting some components along the way is kind of a definition for composition in React. So you have to ask yourself: does it make sense that this component is nested down several levels deep and passes data along it's not interested in? Or can it be on a higher level up the component tree or part of another component so we can remove a whole level on the component tree?

That's always the first step you have to make, when you notice that you have to pass props down several levels deep.

Remember when we talked about passing JSX as children? This comes in handy when you thinkg about composition in React and want to avoid prop drilling. Here's our prop drilling example from above with a better composition:

const productName = 'The best product ever'

<App>
  <Header />
  <MainContent>
    <ProductList productName={productName}>
      <ProductCard>
        <ProductDetailsModal>
          <ProductDetails>
            <ProductHeader />
            <ProductDescription />
            <ProductPrice />
          </ProductDetails>
        </ProductDetailsModal>
      </ProductCard>
    </ProductList>
  </MainContent>
  <Footer />
</App>

function ProductList ({ productName }) {
  return (
    <ProductCard>
      <ProductDetailsModal>
        <ProductDetails>
          <ProductHeader>
            <h1>{productName}</h1>
          </ProductHeader>
          <ProductDescription />
          <ProductPrice />
        </ProductDetails>
      </ProductDetailsModal>
    </ProductCard>
  )
}

In this example, composition in React is used to avoid prop drilling by passing down the necessary props to child components without having to pass them down explicitly at each level. The example demonstrates how to pass the productName prop from the top-level App component down to the ProductHeader component, which is nested several levels deep in the component hierarchy.

To achieve this, the ProductList component accepts the productName prop and renders the ProductCard component with the necessary props. The ProductCard component then renders the ProductDetailsModal component with the necessary props, and so on until the ProductHeader component is rendered.

They main idea here is, that we have to pass the prop only into one component, ProductList. This enables us to give the ProductHeader the productName prop way higher up the component tree. This way we can avoid passing the prop down several levels deep and prop drilling is no longer an issue.

In conclusion, composition in React is a powerful technique that can help to avoid prop drilling, which is a common issue when passing props down several levels in the component tree.

By passing JSX as props we can avoid prop drilling which leads to cleaner and more maintainable code. By using composition, we can create more modular and reusable components, which can be easier to reason about and maintain over time. Overall, composition is a key concept in React development that can lead to more efficient and effective development practices.

Sources & Further Reading

I hope you enjoyed this post and learned something new. If you have any questions, feel free to reach out to me on Twitter Opens in new tab or via Email Opens in new tab.

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I wish you a wonderful day! Marco