Learn React
Managing State

Passing Data Deeply with Context

Usually, you will pass information from a parent component to a child component via props. But passing props can become verbose and inconvenient if you have to pass them through many components in the middle, or if many components in your app need the same information. Context lets the parent component make some information available to any component in the tree below it—no matter how deep—without passing it explicitly through props.

You will learn

  • What “prop drilling” is
  • How to replace repetitive prop passing with context
  • Common use cases for context
  • Common alternatives to context

The problem with passing props

Passing props is a great way to explicitly pipe data through your UI tree to the components that use it.

But passing props can become verbose and inconvenient when you need to pass some prop deeply through the tree, or if many components need the same prop. The nearest common ancestor could be far removed from the components that need data, and lifting state up that high can lead to a situation called “prop drilling”.

Lifting state up

Diagram with a tree of three components. The parent contains a bubble representing a value highlighted in purple. The value flows down to each of the two children, both highlighted in purple.
Diagram with a tree of three components. The parent contains a bubble representing a value highlighted in purple. The value flows down to each of the two children, both highlighted in purple.

Prop drilling

Diagram with a tree of ten nodes, each node with two children or less. The root node contains a bubble representing a value highlighted in purple. The value flows down through the two children, each of which pass the value but do not contain it. The left child passes the value down to two children which are both highlighted purple. The right child of the root passes the value through to one of its two children - the right one, which is highlighted purple. That child passed the value through its single child, which passes it down to both of its two children, which are highlighted purple.
Diagram with a tree of ten nodes, each node with two children or less. The root node contains a bubble representing a value highlighted in purple. The value flows down through the two children, each of which pass the value but do not contain it. The left child passes the value down to two children which are both highlighted purple. The right child of the root passes the value through to one of its two children - the right one, which is highlighted purple. That child passed the value through its single child, which passes it down to both of its two children, which are highlighted purple.

Wouldn’t it be great if there were a way to “teleport” data to the components in the tree that need it without passing props? With React’s context feature, there is!

Context: an alternative to passing props

Context lets a parent component provide data to the entire tree below it. There are many uses for context. Here is one example. Consider this Heading component that accepts a level for its size:

import Heading from './Heading.js';
import Section from './Section.js';

export default function Page() {
  return (
    <Section>
      <Heading level={1}>Title</Heading>
      <Heading level={2}>Heading</Heading>
      <Heading level={3}>Sub-heading</Heading>
      <Heading level={4}>Sub-sub-heading</Heading>
      <Heading level={5}>Sub-sub-sub-heading</Heading>
      <Heading level={6}>Sub-sub-sub-sub-heading</Heading>
    </Section>
  );
}

Let’s say you want multiple headings within the same Section to always have the same size:

import Heading from './Heading.js';
import Section from './Section.js';

export default function Page() {
  return (
    <Section>
      <Heading level={1}>Title</Heading>
      <Section>
        <Heading level={2}>Heading</Heading>
        <Heading level={2}>Heading</Heading>
        <Heading level={2