Code 401: Class 28 - Component Composition

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Questions

1. Can a parent component access the state of a child component? Yes, by using a call back function.

2. What can be passed along in a prop variable? Any and all kinds of data

3. How can a child component “know” the state of another component? This can be done using React Hooks

Vocabulary

• Component Props Properties of components, data that is passed into a component
• Component State this.state, provides the current snapshot of a component
• Application State current snapshot of the entire application

Read: React Basics Recap

• Life cycle of a component: Mounting, Updating, Unmounting
• Higher-order component function that takes a component and returns a new component
• Hooks aim to replace classes

Read: Props.Children

• this.props.children “is used to display whatever you include between the opening and closing tags when invoking a component”

Read: Composition vs Inheritance

• Some components do not know their children ahead of time
• A more specific component can render a generic component and configure it with props
• Facebook has not found a use case for component inheritance hierarchies

Read: React Testing Library API Example

• Provides an example test

Bookmark: React-if Component

Bookmark: React-Testing-Library-Async

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