How to change state of component from anywhere without Redux? - reactjs

Question

Is this bad practices or not ?
export state change function from component
import it from other file.
call the function to change state?
In this way we can change some component state from anywhere.
For example...
We want to change the Model.js state from anywhere.
Modal.js
import React from 'react';
export let toggleModal;
export default class Modal extends React.Component {
constructor(props) {
super(props);
this.state = {
open: false,
};
toggleModal = this.toggleModal;
}
toggleModal = () => {
this.setState({ open: !this.state.open });
};
render() {
const { open } = this.state;
return <div style={{ color: 'red' }}>{open && 'Hello Modal'}</div>;
}
}
App.js(Some Top Level component)
import React from 'react';
import Modal from './Modal';
export default () => (
<>
...
<Modal />
...
</>
);
Somewhere.js
import React from 'react';
import {toggleModal} from './Modal';
export default () => (
<>
<h1>Hello!</h1>
<button onClick={() => toggleModal()}>open Modal!</button>
</>
);
　　
But there is no reference in React Official docs, so is this bad practices ?
What React Docs recommends...
Just passing function props to change parent state from parent to children
Use context
Redux or Mobx
But, these are too complex for me.
Example code here
https://next.plnkr.co/edit/37nutSDTWp8GGv2r?preview

Answer 1

Everything seems pretty much overwhelming and difficult at the beginning. But as we get out hands on them, it's give us more confidence to dig into.
I would recommend to use redux that's how we tackled props drilling problem. You can dispatch a action and connect reducer to corresponding component which upon updating state will re render. This is what I recommend to most of the people to learn the tale of redux with a real life example:
Understanding Redux: The World’s Easiest Guide to Beginning Redux
Apart from this you can take Dan Abramov, author of the library, free redux course on egghead.io:
Getting Started with Redux

Answer 2

The problem you run into, almost immediately like your code example does is this:
It will not work: your toggleModal() method expects a this to refer to an actual component instance. When your onClick() handler fires you invoke toggleModal() as a plain function. The this context will be wrong, and so at best (in your example) you will get an error because you try to invoke something undefined, at worst (in general) you end up invoking the wrong method.
When you think about it, for any non-trivial React component you will have a hard time obtaining a reference to the actual instance that is currently being used: you have to make sure that you are not forgetting to invoke the method on the right component instance and also you have to consider that instances may be created/destroyed 'at will' for whatever reason. For example: what if your component is rendered indirectly as part of some other component's render() method? Multiple layers of indirection like that make it even harder.
Now, you could fix all that by abusing ref with abandon but you will find that now you have to keep track of which ref refers to what particular instance, if you happen to have multiple of the components to consider in one render tree...

Answer 3

Whenever you think one component needs to handle the state of its siblings, the solution is usually to lift the state one level up.
export default class Modal extends React.Component {
render() {
const { isOpen } = this.props;
return <div style={{ color: 'red' }}>{isOpen && 'Hello Modal'}</div>;
}
}
export default class Home {
this.state = {
isOpen: false,
};
toggleModal = () => {
this.setState({ isOpen: !this.state.isOpen });
}
render() {
const { isOpen } = this.state;
return (
<>
<h1>Hello {name}!</h1>
<button onClick={() => this.toggleModal()}>open Modal!</button>
<Modal isOpen={isOpen}/>
<p>Start editing and see your changes reflected here immediately!</p>
</>
)
}
}
This way the Home handle the state and your problem is solved.
This can get annoying if the state needs to be "drilled down" to children, that's a problem than redux or react-context can solve.

Answer 4

Here <Modal /> is the child component. So to call a function in a child component you can simply use Ref.
You can refer this page to get more info about Ref.
You can assign a class variable as a ref to this child and use this class variable as an object to call its function.

Answer 5

I found if in special case, my way is okay.
Special case means something like customAlert component.
It is okay only one instance of customAlert component mounted at a time in App.
To achieve this...
1.Use ref to access and change DOM
2.attach state changing function or component to window and call window.function
3.my case: export state changing function and import it from other file.
And here is how to do with react Context
https://next.plnkr.co/edit/EpLm1Bq3ASiWECoE?preview

Answer 6

I think Redux is overkill if the main thing you are interested in is to make some states-like data available and updatable throughout your App without props drilling.
For that purpose, a much simpler approach (maybe not available at the time the question was posted?) is to use react context: https://frontend.turing.edu/lessons/module-3/advanced-react-hooks.html
"context - an API given to us by React, allowing for the passing of
information to child components without the use of props
[...]
useContext - a react hook, allowing functional components to take
advantage of the context API"