Components Interacting
Learn how to make React components interact with one another.
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Key Concepts
Review core concepts you need to learn to master this subject
props
props
<MyComponent ride="Millennium Falcon"/>
// MyComponent is the component and ride is the attribute. Ride will be used to pass the information to another component. Components can pass information to other components. The transferring of this information is called props. In order to pass information from one component to another, it needs an attribute. The code snippet above demonstrates the use of attributes in props.
this.props
this.props
<MyComponent ride="Millennium Falcon"/>
// MyComponent is the component and ride is the attribute. Ride will be used to pass the information to another component. In React Components you can access the component’s props by using the this.props object. this.props uses the props name as the key and their values are the values passed in JSX. The code block above demonstrates how this.props can be used.
defaultProps
defaultProps
<MyComponent ride="Millennium Falcon"/>
// MyComponent is the component and ride is the attribute. Ride will be used to pass the information to another component. A React component defaultProps object contains default values to be used in case props are not passed. If a prop is not passed on to a component, then it will be replaced with the value in the defaultProps object. The code block above demonstrates how a defaultProps object can be used.
this.props.children
this.props.children
<MyComponent ride="Millennium Falcon"/>
// MyComponent is the component and ride is the attribute. Ride will be used to pass the information to another component. Every component’s props object has a property named children. Using this.props.children will return everything inbetween a component’s opening and closing JSX tags.
- 1A React application can contain dozens, or even hundreds, of components. Each component might be small and relatively unremarkable on its own. When combined, however, they can form enormous, fant…
- 2Here is a .render() method that returns an HTML-like JSX element: class Example extends React.Component { render() { return Hello world ; } } You’ve seen render methods return s, s,…
- 3This is new territory! You’ve never seen a component rendered by another component before. You have seen a component rendered before, though, but not by another component. Instead, you’ve seen …
- 4When you use React.js, every JavaScript file in your application is invisible to every other JavaScript file by default. ProfilePage.js and NavBar.js can’t see each other. This is a probl…
- 5Alright! You’ve learned how to use import to grab a variable from a file other than the file that is currently executing. When you import a variable from a file that is not the current file, th…
- 6Now you’re ready for to render ! All that’s left to do is render .
- 1Previously, you learned one way that components can interact: a component can render another component. In this lesson, you will learn another way that components can interact: a component can …
- 2Every component has something called props. A component’s props is an object. It holds information about that component. To see a component’s props object, you use the expression this.props. He…
- 3You can pass information to a React component. How? By giving that component an attribute: Let’s say that you want to pass a component the message, “This is some top secret info.”. Here’…
- 4You just passed information to a component’s props object! You will often want a component to display the information that you pass. Here’s how to make a component display passed-in informati…
- 5You have learned how to pass a prop to a component: You have also learned how to access and display a passed-in prop: render() { return {this.props.firstName} ; } The most common use of pro…
- 6Awesome! You passed a prop from a component to a different component, accessed that prop from the receiver component, and rendered it! You can do more with props than just display them. You can …
- 7You can, and often will, pass functions as props. It is especially common to pass event handler functions. In the next lesson, you will pass an event handler function as a prop. However, you h…
- 8Good! You’ve defined a new method on the Talker component class. Now you’re ready to pass that function to another component. You can pass a method in the exact same way that you pass any othe…
- 9Great! You just passed a function from to . In the code editor, select Button.js. Notice that Button renders a element. If a user clicks on this element, then you want your passed-…
- 10Let’s talk about naming things. When you pass an event handler as a prop, as you just did, there are two names that you have to choose. Both naming choices occur in the parent component class…
- 11Every component’s props object has a property named children. this.props.children will return everything in between a component’s opening and closing JSX tags. So far, all of the components that…
- 12Take a look at the Button component class. Notice that on line 8, Button expects to receive a prop named text. The received text will be displayed inside of a element. What if nobody passes a…
- 13That completes our lesson on props. Great job sticking with it! Here are some of the skills that you have learned: - Passing a prop by giving an attribute to a component instance - Accessing …
- 1Dynamic information is information that can change. React components will often need dynamic information in order to render. For example, imagine a component that displays the score of a bas…
- 2A React component can access dynamic information in two ways: props and state. Unlike props, a component’s state is not passed in from the outside. A component decides its own state. To ma…
- 3To read a component’s state, use the expression this.state.name-of-property: class TodayImFeeling extends React.Component { constructor(props) { super(props); this.state = { mood: ‘dec…
- 4A component can do more than just read its own state. A component can also change its own state. A component changes its state by calling the function this.setState(). this.setState() takes tw…
- 5The most common way to call this.setState() is to call a custom function that wraps a this.setState() call. .makeSomeFog() is an example: class Example extends React.Component { constructor(pr…
- 6There’s something odd about all of this. Look again at Toggle.js. When a user clicks on the , the .changeColor() method is called. Take a look at .changeColor()’s definition. .changeColo…
- 7In this unit, you learned how to use import and export to access one file from another. You learned about props and state, and the countless variations on how they work. Before this unit, you lea…
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Components Interacting
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