React useContext() hook introduction 🧗♂️
Summary
TLDRThe video script explains the use of React's useContext hook for sharing values across multiple component levels without prop drilling. It guides through creating a nested component structure (A to D), setting up state in Component A, and using createContext to create a 'userContext'. It then demonstrates how Component D accesses the username from Component A without passing props through intermediate components, simplifying state sharing in complex component trees.
Takeaways
- 😀 The useContext hook in React allows for sharing values between multiple components without passing props down through every level.
- 📁 The script demonstrates building four components (A, B, C, and D), each nested inside the other.
- 🖱 Component A manages the state using useState, storing a 'user' value and setter, which will be shared across components.
- 💡 Prop drilling involves passing props through several nested components, but this method becomes tedious in deeply nested structures.
- 🛠 The useContext hook helps to avoid prop drilling by enabling direct access to values from any nested component.
- 🌍 The provider component (Component A) wraps child components and provides access to the shared value using the context API.
- 🧩 Consumers, such as Component D, can access the shared value by using the useContext hook, connecting them to the nearest provider.
- 📜 The script outlines three steps for setting up context: importing createContext, creating context, and wrapping child components within the provider.
- 📝 The context consumer can access the shared values by importing both useContext and the context created in Component A.
- 🔁 The useContext hook allows components to access shared data directly, making the flow of data simpler and eliminating the need for passing props down.
Q & A
What is the main purpose of the `useContext` hook in React?
-The `useContext` hook in React allows you to share values between multiple levels of components without passing props through each level, making it easier to manage state across deeply nested components.
What problem does the `useContext` hook solve?
-The `useContext` hook solves the problem of prop drilling, where props have to be passed down through many levels of nested components. By using `useContext`, you can provide data directly to any component in the tree without the need for intermediate components to pass props.
How do you set up a context provider in React?
-To set up a context provider, first import `createContext` from React, then create a context using `const MyContext = createContext()`. In the component where you want to provide the context, wrap the children components with `MyContext.Provider`, and set its value to the data you want to share.
What are the steps to use `useContext` in a consumer component?
-To use `useContext` in a consumer component, follow these steps: 1) Import the `useContext` hook and the context you want to use. 2) Inside the component, call `const value = useContext(MyContext)` where `MyContext` is the context you created. This gives you access to the shared data.
Why is prop drilling considered tedious in React?
-Prop drilling is considered tedious because it requires passing props through multiple layers of components, even when only the deeply nested components need the data. This can make the code harder to maintain and debug, especially as the component tree grows.
How do you create and export a context in React?
-To create and export a context in React, you first import `createContext` from React, then define a context with `const MyContext = createContext()`. Finally, export the context with `export const MyContext` so it can be used in other components.
How does a component become a consumer of a context in React?
-A component becomes a consumer of a context in React by using the `useContext` hook. You import both the `useContext` hook and the context you want to consume, then call `useContext` within the component to access the context’s value.
What does the context provider's `value` prop do?
-The `value` prop of the context provider defines the data that will be shared with the components consuming the context. Any component that uses the `useContext` hook with this context will have access to the `value` provided.
In the example, how is the username passed from `Component A` to `Component D` without props?
-The username is passed from `Component A` to `Component D` without props by wrapping `Component B` inside `Component A` with the `UserContext.Provider` and setting the `value` to the username. `Component D` then uses the `useContext` hook to directly access the username from the `UserContext`.
How can you access the context value in multiple components without repeating code?
-You can access the context value in multiple components without repeating code by using the `useContext` hook in each component that needs the value. Since the context value is provided at a higher level, any component that consumes the context can directly access the value.
Outlines
🛠️ Introduction to useContext in React
This paragraph introduces the `useContext` hook in React, explaining that it allows for sharing values between multiple levels of components without having to pass props down each level. The example provided involves four nested components (A through D). The user begins by creating a file for Component A, exporting a basic JSX function that returns a div element with an H1 header for visualization. The tutorial also includes CSS adjustments for layout, followed by duplicating this setup for components B, C, and D, modifying their references accordingly. This setup lays the foundation for prop drilling, which will later be avoided using `useContext`.
🔄 Prop Drilling Across Components
This paragraph explains prop drilling in React. Starting with Component A, a `user` state variable is created to store a username. The username is displayed in an H2 element within Component A. To display the username in Component D, the value must be passed through each component in the hierarchy (B, C, and finally D). Each component in this chain accepts `props` and passes the user data along. In Component D, the username is displayed in an H2 element. This process of passing props through multiple levels is described as prop drilling, which becomes cumbersome in deeply nested structures.
⚙️ Solving Prop Drilling with useContext
This paragraph introduces the `useContext` hook as a solution to prop drilling. Instead of passing props through every component, `useContext` allows direct access to values across components. The provider component (Component A) will store the data (username) and make it accessible to other components. The steps include importing `createContext` from React, creating a `UserContext`, and wrapping Component B with the provider. By setting the provider’s value to `user`, Component A becomes the source of the data. The need for props in the child components is eliminated, simplifying the component structure.
👥 Using Context in Consumer Components
This paragraph describes how consumer components, such as Component D, access values using `useContext`. Component D imports the `useContext` hook and the `UserContext` created earlier. Inside the component, the `user` value is retrieved by passing `UserContext` to `useContext`. The username is then displayed in the H2 element of Component D, demonstrating the elimination of prop drilling. The paragraph emphasizes that this method provides a more efficient way of accessing data across components compared to passing props through each level.
📋 Expanding Context Usage Across Components
In this paragraph, the same `useContext` logic is applied to Component C. The code for accessing the context is copied from Component D, as both components need the same data (username). By doing so, the username is displayed again in Component C with an additional H2 element. This shows that any child component of the provider (Component A) can access the shared data without having to receive it via props. This solution highlights the flexibility of `useContext` in avoiding repetitive code and prop drilling in React applications.
✅ Conclusion: Benefits of useContext
The final paragraph summarizes the benefits of the `useContext` hook in React. It reiterates that `useContext` allows data to be shared across multiple levels of components without passing props down the chain. This method is especially useful when working with deeply nested components, as it avoids the tedious process of prop drilling. The tutorial concludes by reaffirming the simplicity and efficiency of `useContext` in managing shared data within React applications.
Mindmap
Keywords
💡useContext
💡Prop Drilling
💡createContext
💡Provider
💡Consumer
💡useState
💡Nested Components
💡JSX
💡Template Strings
💡Component Tree
Highlights
Introduction to the useContext hook in React, which allows sharing values between multiple levels of components without passing props through each level.
Explanation of how useContext simplifies the process compared to prop drilling, where props are passed through each component in the hierarchy.
Steps to create the component hierarchy: Component A, B, C, and D, where each component nests within the next.
Detailed instructions on how to create a state variable using useState in Component A, which holds the user’s username.
Illustration of how prop drilling works: passing the 'user' prop from Component A to D through B and C.
Explanation of the tediousness of prop drilling, which leads to the introduction of the useContext hook as a better solution.
How to set up a provider component in Component A using createContext from React to provide the 'user' value.
Detailed steps on how to wrap child components within the provider in Component A to share data using useContext.
Removing props from child components (B, C, D) and refactoring them to consume context values instead of receiving props.
Explanation of how consumer components, like Component D, access the context by using the useContext hook.
Implementation of useContext in Component D, allowing it to access the 'user' value from the context without prop drilling.
Replication of the same steps in Component C to access the context using useContext.
Demonstration of the flexibility of useContext, allowing multiple child components to access the same shared value without passing props.
Final summary of the advantages of useContext over prop drilling, emphasizing its efficiency in deeply nested component structures.
Practical example of useContext in action, where user data is displayed in both Component C and D without the need for prop chains.
Transcripts
hey everybody today I got to explain use
context in react use context is a react
hook it allows you to share values
between multiple levels of components
without passing props through each level
what we'll do in this example is create
four components components a through D
each component will be nested within one
another so within our source folder
let's create a new file for component a
this will be a jsx file we will create a
function based component named component
a no parameters for now and be sure to
export it export default component
a within this component we will return
some HTML we will return a div
element the div element will have a
class name of
box within the div element we will
create an H1 element
that has text of component
a within our app component we will
import component
a import component
a from its
location component a.
jsx we will return a single component a
component we're also going to add a
little bit of CSS to visualize it we
will select our class of box add a
border of three pixel
solid and padding of 25
pixels here's component
a we're going to copy this file of
component
a and paste it three
times we will rename the second copy as
component
B the third as component
C
the fourth as component
D we have component a b c and d within
component B rename any instance of
component a with component
B the same goes for
C and
D from component a we're going to import
component B
import component B from its
location component b.
jsx after our H1 element we will include
one component B
component we have component B within
component a now within component B we
will import component
C import component C from its
location
component c.
jsx after our H1 element we will include
one component C
component so we have component C within
component B within component a within
component C we will import component D
import component D from its
location component d.
jsx after H1 element we will include one
component D
component we have component D within
component C within component B within
component a I've organized my tabs a b c
d within component a we're going to
create a state
variable const user and a Setter for
user equals the US state hook we will
need to import
it type in your username I'll type in
bro code for
mine at the top we need to import from
react use object destructuring to get
the use State Hook from its location of
react now after our H1 element I will
create an H2 heading we will embed some
JavaScript we'll display a template
string of
hello add a
placeholder your username
name So within component a you should
have an H2 heading that displays hello
and your username within component D
what if I would also like to display my
username well from component a I would
have to pass props down all the way to
component D I'll have to pass them to B
which will pass them to C which will
pass them to D so if we were using props
this is what we would have to do within
component component B we will pass in
props set user to equal our user within
component B we'll have to set up
props props will be the parameter within
component C we will set user to equal
embed some JavaScript props do user
within component C we'll set up props
again within component D we will set
user to equal embeds JavaScript props do
user then within component D set up
props again after our H1 element let's
create an H2 element we'll embed some
JavaScript use a template string display
by add a
placeholder access props our parameter
access the
user within component a we have hello
your username within component D we have
by
your username by passing props down each
of these nested components this is known
as prop drilling where drilling down to
the center the center component passing
props down this long chain can become
very tedious but there's a better
solution and that is with the use
context hook the use context hook allows
us to share values between multiple
levels of components without passing
props down through each level however we
have to set up a provider component
component which component has the data
we would like access to in this case it
would be component a in component a we
have that state variable of our username
which we named user So within our
provider component we have three steps
we have to import create context from
react So within component a we already
have used state but we also need create
context we need to create some context
and Export it
export const then we need a unique name
for this context we're working with the
username let's name our context user
context the context name should be
descriptive of what you're working with
if the data we're working with is a
color we could say color context equals
create context and this is a
function now the last thing we need to
do is wrap any children components
within this special provider
component we are going to wrap component
B within another component we will take
our user
context access provider set the value
equal to be some Java Script our value
of
user and we just need to wrap this
component of component
B component a is now the provider
component it's going to provide a value
of user we no longer need props we can
get rid of these for each
component after I deleted props from
component B well our username is now
undefined within component D we broke
that
chain all right any component that needs
this data we will set up to be a
consumer component you can have more
than one we'll have to import the use
context Hook from react as well as the
context that we set up we're exporting
it so we need to import it elsewhere
within component D we will import from
react use object
destructuring the use context Hook from
its location of
react we also need the user
context import use object destructuring
to get user context from its
location of component
a that was the original location where
we exported it
from we'll use the context get the
context and store the value we'll do
that inside of our component
const user
equals use context hook we're going to
pass in our user context as an argument
and now we have access to
user we'll use a placeholder and add our
user and that has appeared to work we
have displayed by your
username we have avoided prop drilling
instead of drilling down to the center
component to pass down a value by using
use context we Traverse up the component
tree to find the nearest provider which
would be component a component a is the
provider component component D is a
consumer component and you can have more
than one so let's do the same thing with
component C we need these two lines of
code really we can just copy them
because I'm
lazy and we need to create a con
of user or some other descriptive name
for this value use context pass in our
context of user
context let's add another H2 element
we'll embed some JavaScript use a
template string let's say hello again
add a placeholder our
username So within component C we have
used use context again without prop
Drilling we're displaying hello again
your
username any component that's a child
component of our provider component of a
has access to this value that we set up
all right everybody so that is the use
context react hook it allows you to
share values between multiple levels of
components without passing props through
each level if you have a lot of nested
components passing props down to each
level can become very tedious this is a
way to avoid that and well everybody
that is the use context hook in
react
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