I am using react-use-intercom.
Using following hook from the guide react-use-intercom which suggests to use functional components everywhere.
const { boot, shutdown, hide, show, update } = useIntercom();
However I am using class components everywhere, is there any way that I can do use it in class component itself, because the official documentation has examples in functional component only.
I want to use this methods on click of a button, i.e on some events.
You cannot use hooks in class component, which is a rule from React. There is a way to get pass that. You can create a functional component with useIntercom, pass the state or function as props to your class component. For example:
function Intercom(){
const intercom = useIntercom();
return <YourComponent {...intercom} />
}
For example, you now can use the boot function in your component like
this.props.boot()
Related
I was trying to implement a drag and drop functionality to my ant design tabs component. The example they mentioned in the documentation is class based. I was trying to make it into function component but I am not sure what props are in this case.
Ant design demo
Official documentation
For example, I got confused here, this class component itself is outside another class component. How would react extract these connectDragSource, connectDropTarget, children when it has noting that is being passed from the props? And how would I extract these when I am in a function component?
class TabNode extends React.Component {
render() {
const { connectDragSource, connectDropTarget, children } = this.props;
return connectDragSource(connectDropTarget(children));
}
}
and there are some other aspects in the provided demo that are confusing to me. It would be great help if you could breakdown and explain what is happening so that I can turn this into a react functional component.
In functional component you can access props as one of your component's argument, and also instead of returning your JSX by render method, whatever you returns by your functional component, considers as your JSX output, like this:
function MyComp(props){
// do whatever you want by props (actually body of your function is equivalent to render method in class component)
return (<div>...</div>);
}
Here I implemented your tab example by function component.
I'm learning React and came across Context API, while looking at sample code I found it has got render () function
Per my understanding Context react class component is there to manage state, so it's not clear why do we need to use render( ) function ?
Class components have render methods. Class components can access the Context API but the render method is completely decoupled from the Context API.
const App = () => (
<View>
<Text>Test</Text>
</View>
)
class App extends Component {
render() {
return (
<View>
<Text>Test</Text>
</View>
);
}
}
When I test, two things are the same.
Please tell me the difference between these two.
A Class Component is a stateful component and const App is a stateless (or functional) component.
A stateful component is used to:
initialize the state
modify the state
render something
Additionally it has lifecycle methods.
Whereas a stateless component is often just used to return a piece of UI.
In short: a class component is more powerful than a functional component
EDIT:
Since React Native 0.59 also functional components can have a state. See Hooks-Intro for more information.
Using class you can access life cycle hook and you can store a state in the class. Using class you can build stateful component or smart component. Meaning that you handle logic in your class component like doing http request
Using functional component. In this case is const you can build dump component or stateless component (component only use to display data). This is a great way to keep your react code maintainable and readable. Breaking it up into smaller components and passing props to child components.
You can read it more here because is very long expain so I just give you brief overview
Regards
Class will be for containers components. "smart" functional component that conatins State. and data and previewing "dumb" view components.
The "dumb" functional component is used to preview something or better say. render something that is usualy sent from a container.
Now days using hooks you can get the whole life cycle of the class component in a functional component. The only difference is that the functional is state less!
I'm quite new in this react ecosystem, but it's pretty clear so far on what a component is and how to create one using:
export default class NotificationsScreen extends Component {
render() {
return(<View></View>);
}
}
however I've seen some examples that just use
const MySmallComponent = (props) => <View></View>
And the app seems to work just as fine..
What is the advantage of extending Component?
Since React is strongly connected to functional programming, it's always a good habit to write pure functions in React. If your component doesn't need to manage state or involve lifecycle methods then use stateless component:
It just feels more natural that way
Easier to write, easier to read
No extends, state and lifecycle methods mean faster code
You can even find more reasons at this article. So, all I want to say is, always use stateless component if you don't need to manage its state.
Dan Abramov coined the terms Smart and Dumb components. Later, he called them Container and Presentational components. So
export default class NotificationsScreen extends Component {
render() {
return(<View></View>);
}
}
is a Container and
const MySmallComponent = (props) => <View></View>
is Presentational components.
Presentational Components are only used for presentaion purposes i.e they rarely have their own state and they are just used to show data on UI by receiving props from parent component or include many child component inside of them. Presentational Component don't make use of react lifecycle methods.
Where as Smart components or Containers usually have state of their own and make use of lifecycle methods of react and also these components usually have their own state.
I am reading this and it says:
When a component is purely a result of props alone, no state, the
component can be written as a pure function avoiding the need to
create a React component instance.
What's the difference between a component and a component instance ?
Are they the same ?
EDIT:
What is the difference between Component and Component Instance ?
How do they relate to each-other ?
Conceptually ?
How are they represented in computer memory? How does the representation differ ?
What is a component and what is an instance of that component ? (In memory.) What kind of JS Object ?
Instance in what sense ? Object oriented sense ?
Is it true that every component can have (one or more) instance(s) ?
How many instances can a component have ?
Does it even make sense to say that an instance can be created for a/every react component ?
How are react component instances created and how are components created ?
Reason for asking:
I am trying to create a concept map of react to clarify the terminology and how they relate to each other.
Here is a draft:
The basic difference is, when it a Component, React will run/add all its Lifecycle methods. This will be useful when you have state in your component. When you use this component, React will create a React Component Instance which will have all the lifecycle methods and other hooks added to it.
class App extends React.Component{
...
}
In some cases, you won't use state. In those cases, adding all those lifecycle methods are unnecessary. So, React gives you an way to create an component which will have render alone. It is called PureComponent. When you use this, there is no need to create a new Component Instance because there is no lifecycle methods here. It'll just be a function which can take props and return React Elements.
class App extends React.PureComponent{
...
}
Hope this helps!
[Update]
What is a Component and a Component Instance?
Technically, a Component in React is a class or a function.
Example:
class App extends React.Component{
...
}
//stateless component
const App = (props) => {
...
}
When you use that component, it'll be instantiated, more like new App(). But, React does it by itself in a different way.
For Example:
render(){
return <App/> //Instance of the component App
}
Instances are required because, each instance can perform individually. Instances are a copy of original class.
Simple answer is, components will be a Class and component Instance will be the copy/instance of the class and will be used in render
Hope this explains!
A "React component instance" is just an instance that was created from a previously defined class component. See the example below (es6/JSX) which contains both props and state:
class MyComponentClass extends React.Component {
constructor(props) {
super(props);
// Set initial state
this.state = {
example: 'example'
};
}
render() {
return <div>
<div>{this.state.example}</div>
<div>{this.props.example}</div>
</div>;
}
}
If you have no need for state in your component you can use a pure, stateless, functional React component like so:
function MyStatelessFunctionalComponent(props) {
return <div>{this.props.example}</div>;
}
Here is some more information about stateless React components when they were introduced in React v0.14. Since then you have the ability to use hooks starting in React v16.8, which allow you to define a functional component that has state or makes use of the component lifecyle.
As mentioned in some other comments, there are many performance benefits when using stateless components. These types of components are perfect for when you want something purely presentational as an example.
Since there’s no state or lifecycle methods to worry about, the React team plans to avoid unnecessary checks and memory allocations in future releases.