How to pass parameters in react functions with Typescript - reactjs

Here is the structure of my folder:
src--|
|--ComponentsFolder1--Button.tsx
|--ComponentsFolder2--ParentDiv.tsx
My problem is as follows:
Button.tsx is a react component which calls a fetch function located in react ParentDiv.tsx with a few parameters:
type getNewVerseProps = {
getNewVerseFunc: (event: React.MouseEvent<HTMLDivElement>) => string;
};
const Button = ({ getNewVerseFunc }: getNewVerseProps) => {
return (
<div>
<div
onClick={getNewVerseFunc.bind(name, id)}>
</div>
</div>
Now, as you can see, I want to call the function on my ParentDiv.tsx file with the specified parameters in Button.tsx:
const getNewVerseFunc = async (name: string, id: string) => {
const requ = await fetch(
`https://api.scripture.api.bible/${name}/${id}`,
{
method: "GET",
headers: {
"api-key": bibleApi,
},
}
};
<Button getNewVerseFunc={getNewVerseFunc}/>
My problem is that the params in the function are not being passed down in the Button component when i call the getNewVerseFunc function in the ParentDiv component

First of all you've used bind wrongly. First argument is a context, which is in this case ignored, because you have an arrow function, which is instantly bound; but it is impossible to rebind bound function.
Common practice is to have button with onClick callback, like:
import { FunctionComponent } from 'react';
type Props {
onClick: MouseEventHandler;
}
const Button: FunctionComponent<Props> = ({ onClick, children }) => (
<div onClick={getNewVerseFunc.bind(name, id)}>
{children}
</div>
);
And for simplicity avoid using bind, call or apply if possible; it's good that you are aware of these functions, but using them usually reduces readability.
Then in parent you can do the following:
import { FunctionComponent } from 'react';
const ParentDiv: FunctionComponent = () => {
const name = 'Some name';
const id = 'Some id';
return (
<Button onClick={() => getNewVerseFunc(name, id)}>
Click me
</Button>
);
};
If your Button component is wrapped with memo, then it makes sense to use useCallback hook for onClick handler, but that's already micro optimisation.

Related

Use context for communication between components at different level

I'm building the settings pages of my apps, in which we have a common SettingsLayout (parent component) which is rended for all the settings page. A particularity of this layout is that it contains an ActionsBar, in which the submit/save button for persisting the data lives.
However, the content of this SettingsLayout is different for each page, as every one of them has a different form and a different way to interact with it. For persisting the data to the backend, we use an Apollo Mutation, which is called in one of the child components, that's why there is no access to the ActionsBar save button.
For this implementation, I thought React Context was the most appropriated approach. At the beginning, I thought of using a Ref, which was updated with the submit handler function in each different render to be aware of the changes.
I've implemented a codesandbox with a very small and reduced app example to try to illustrate and clarify better what I try to implement.
https://codesandbox.io/s/romantic-tdd-y8tpj8?file=/src/App.tsx
Is there any caveat with this approach?
import React from "react";
import "./styles.css";
type State = {
onSubmit?: React.MutableRefObject<() => void>;
};
type SettingsContextProviderProps = {
children: React.ReactNode;
value?: State;
};
type ContextType = State;
const SettingsContext = React.createContext<ContextType | undefined>(undefined);
export const SettingsContextProvider: React.FC<SettingsContextProviderProps> = ({
children
}) => {
const onSubmit = React.useRef(() => {});
return (
<SettingsContext.Provider value={{ onSubmit }}>
{children}
</SettingsContext.Provider>
);
};
export const useSettingsContext = (): ContextType => {
const context = React.useContext(SettingsContext);
if (typeof context === "undefined") {
/*throw new Error(
"useSettingsContext must be used within a SettingsContextProvider"
);*/
return {};
}
return context;
};
function ExampleForm() {
const { onSubmit } = useSettingsContext();
const [input1, setInput1] = React.useState("");
const [input2, setInput2] = React.useState("");
onSubmit.current = () => {
console.log({ input1, input2 });
};
return (
<div className="exampleForm">
<input
placeholder="Input 1"
onChange={(event) => setInput1(event.target.value)}
/>
<input
placeholder="Input 2"
onChange={(event) => setInput2(event.target.value)}
/>
</div>
);
}
function ActionsBar() {
const { onSubmit } = useSettingsContext();
return (
<section className="actionsBar">
<strong>SETTINGS</strong>
<button onClick={() => onSubmit?.current()}>Save</button>
</section>
);
}
export default function App() {
return (
<div className="App">
<SettingsContextProvider>
<ActionsBar />
<ExampleForm />
</SettingsContextProvider>
</div>
);
}
The main caveat I see in this approach is that you change the whole submit function when you need only reaction to submit event. Event is the catch, I think.
Your approach works ok, but has no extension points, for cases such as validation etc.
So I propose to use EventEmitter in any form (better with types support) as a context value e.g. communication channel.
This is a fork of your codesandbox that illustrates this approach:
https://codesandbox.io/s/friendly-fog-qlrusj?file=/src/App.tsx

REACT: How to set the state in the child and access it in the parent, receiving undefined

I am building this project to try and improve my understanding of react :), so I am a n00b and therefore still learning the ropes of extracting components, states, props etc =)
I have a child Component DescriptionDiv, its parent component is PlusContent and finally the parent component is PlusContentHolder. The user types some input into the DescriptionDiv which then, using a props/callback passes the user input to the PlusContent.
My question/problem is: after setting useState() in the PlusContent component, I am after a button click in the PlusContentHolder component, returned with an undefined in the console.log.
How come I cannot read the useState() in the next parent component, the PlusContentHolder?
I know that useState() is async so you cannot straight up call the value of the state in the PlusContent component, but shouldn't the state value be available in the PlusContentHolder component?
below is my code for the DescriptionDiv
import './DescriptionDiv.css';
const DescriptionDiv = props => {
const onDescriptionChangeHandler = (event) => {
props.descriptionPointer(event.target.value);
}
return (
<div className='description'>
<label>
<p>Description:</p>
<input onChange={onDescriptionChangeHandler} type='text'></input>
</label>
</div>);
}
export default DescriptionDiv;
Next the code for the PlusContent comp
import React, { useState } from "react";
import DescriptionDiv from "./div/DescriptionDiv";
import ImgDiv from "./div/ImgDiv";
import "./PlusContent.css";
import OrientationDiv from "./div/OrientationDiv";
const PlusContent = (props) => {
const [classes, setClasses] = useState("half");
const [content, setContent] = useState();
const [plusContent, setPlusContent] = useState({
orientation: "left",
img: "",
description: "",
});
const onOrientationChangeHandler = (orientationContent) => {
if (orientationContent == "left") {
setClasses("half left");
}
if (orientationContent == "right") {
setClasses("half right");
}
if (orientationContent == "center") {
setClasses("half center");
}
props.orientationInfo(orientationContent);
};
const onDescriptionContentHandler = (descriptionContent) => {
props.descriptionInfo(setPlusContent(descriptionContent));
console.log(descriptionContent)
};
const onImageChangeHandler = (imageContent) => {
props.imageInfo(imageContent);
setContent(
<>
<OrientationDiv
orientationPointer={onOrientationChangeHandler}
orientationName={props.orientationName}
/> {/*
<AltDiv altPointer={onAltDivContentHandler} />
<TitleDiv titlePointer={onTitleDivContentHandler} /> */}
<DescriptionDiv descriptionPointer={onDescriptionContentHandler} />
</>
);
};
return (
<div className={classes}>
<ImgDiv imageChangeExecutor={onImageChangeHandler} />
{content}
</div>
);
};
export default PlusContent;
and lastly the PlusContentHolder
import PlusContent from "../PlusContent";
import React, { useState } from "react";
const PlusContentHolder = (props) => {
const onClickHandler = (t) => {
t.preventDefault();
descriptionInfoHandler();
};
const descriptionInfoHandler = (x) => {
console.log(x) // this console.log(x) returns and undefined
};
return (
<div>
{props.contentAmountPointer.map((content) => (
<PlusContent
orientationInfo={orientationInfoHandler}
imageInfo={imageInfoHandler}
descriptionInfo={descriptionInfoHandler}
key={content}
orientationName={content}
/>
))}
<button onClick={onClickHandler}>Generate Plus Content</button>
</div>
);
};
export default PlusContentHolder;
The reason why the descriptionInfoHandler() function call prints undefined in its console.log() statement when you click the button, is because you never provide an argument to it when you call it from the onClickHandler function.
I think that it will print the description when you type it, however. And I believe the problem is that you need to save the state in the PlusContentHolder module as well.
I would probably add a const [content, setContent] = useState() in the PlusContentHolder component, and make sure to call setContent(x) in the descriptionInfoHandler function in PlusContentHolder.
Otherwise, the state will not be present in the PlusContentHolder component when you click the button.
You need to only maintain a single state in the PlusContentHolder for orientation.
Here's a sample implementation of your use case
import React, { useState } from 'react';
const PlusContentHolder = () => {
const [orientatation, setOrientation] = useState('');
const orientationInfoHandler = (x) => {
setOrientation(x);
};
const generateOrientation = () => {
console.log('orientatation', orientatation);
};
return (
<>
<PlusContent orientationInfo={orientationInfoHandler} />
<button onClick={generateOrientation}>generate</button>
</>
);
};
const PlusContent = ({ orientationInfo }) => {
const onDescriptionContentHandler = (value) => {
// your custom implementation here,
orientationInfo(value);
};
return <DescriptionDiv descriptionPointer={onDescriptionContentHandler} />;
};
const DescriptionDiv = ({ descriptionPointer }) => {
const handleChange = (e) => {
descriptionPointer(e.target.value);
};
return <input type="text" onChange={handleChange} />;
};
I would suggest to maintain the orientation in redux so that its easier to update from the application.
SetState functions do not return anything. In the code below, you're passing undefined to props.descriptionInfo
const onDescriptionContentHandler = (descriptionContent) => {
props.descriptionInfo(setPlusContent(descriptionContent));
};
This shows a misunderstanding of the use of state. Make sure you're reading about "lifting state" in the docs.
You're also declaring needless functions, e.g. onDescriptionContentHandler in your PlusContent. The PlusContent component could just pass the descriptionInfoHandler from PlusContentHolder prop directly down to DescriptionDiv, since onDescriptionContentHandler doesn't do anything except invoke descriptionInfoHandler.
You may want to consider restructuring your app so plusContent state is maintained in PlusContentHolder, and pass that state down as props. That state would get updated when DescriptionDiv invokes descriptionInfoHandler. It'd subsequently pass the updated state down as props to PlusContent.
See my suggested flowchart.

Observe (get sized) control (listen to events) over a nested component in the react and typescript application via the forwardRef function

I have a functional component called MyDivBlock
const MyDivBlock: FC<BoxProps> = ({ }) => {
{getting data...}
return (
<>
<div className='divBlock'>
{data.map((todo: { id: string; title: string }) =>
<div key={todo.id}>{todo.id} {todo.title} </div>)}
</div>
</>
);
};
I use it in such a way that MyDivBlock is nested as a child of
const App: NextPage = () => {
return (
<div>
<Box >
<MyDivBlock key="key0" areaText="DIV1" another="another"/>
</Box>
</div>
)
}
Note that MyDivBlock is nested in Box and MyDivBlock has no ref attribute. This is important because I need to write Box code with no additional requirements for my nested children. And anyone who will use my Box should not think about constraints and ref attributes.
Then I need to get the dimensions of MyDivBlock in the code of Box component, and later attach some event listeners to it, such as scrolling. These dimensions and listeners will be used in the Box component. I wanted to use Ref to control it. That is, the Box will later observe changes in the dimensions and events of MyDivBlock by creating a ref-reference to them
I know that this kind of parent-child relationship architecture is implemented through forwardRef
And here is the Box code:
import React, { forwardRef, useImperativeHandle, useRef } from 'react';
export interface BoxProps extends React.ComponentProps<any> {
children?: Element[];
className: string;
}
export const Box: React.FC<BoxProps> = ({ children, ...rest }: BoxProps): JSX.Element => {
const childRef = useRef<HTMLDivElement>();
const ChildWithForwardRef = forwardRef<HTMLDivElement>((props, _ref) => {
const methods = {
show() {
if (childRef.current) {
console.log("childRef.current is present...");
React.Children.forEach(children, function (item) {
console.log(item)})
console.log("offsetWidth = " + childRef.current.offsetWidth);
} else {
console.log("childRef.current is UNDEFINED");
}
},
};
useImperativeHandle(_ref, () => (methods));
return <div ref={childRef}> {children} </div>
});
ChildWithForwardRef.displayName = 'ChildWithForwardRef';
return (
<div
className={'BoxArea'}>
<button name="ChildComp" onClick={() => childRef.current.show()}>get Width</button>
<ChildWithForwardRef ref={childRef} />
</div>
);
}
export default Box;
The result of pressing the button:
childRef.current is present...
[...]
$$typeof: Symbol(react.element) key: "key0" props: {areaText: 'DIV1', another: 'another'}
[...] Object
offsetWidth = undefined
As you can see from the output, the component is visible through the created ref. I can even make several nested ones and get the same for all of them.
But the problem is that I don't have access to the offsetWidth and other properties.
The other challenge is how can I add the addEventListener?
Because it works in pure Javascript with their objects like Element, Document, Window or any other object that supports events, and I have ReactChildren objects.
Plus I'm using NextJS and TypeScript.
Didn't dive too deep into the problem, but this may be because you are passing the same childRef to both div inside ChildWithForwardRef and to ChildWithForwardRef itself. The latter overwrites the former, so you have the method .show from useImperativeHandle available but not offsetWidth. A quick fix is to rewrite ChildWithForwardRef to use its own ref:
const ChildWithForwardRef = forwardRef<HTMLDivElement>((props, _ref) => {
const ref = useRef<HTMLDivElement>()
const methods = {
show() {
if (ref.current) {
console.log("ref.current is present...");
React.Children.forEach(children, (item) => console.log(item))
console.log("offsetWidth = " + ref.current.offsetWidth);
} else {
console.log("ref.current is UNDEFINED");
}
},
};
useImperativeHandle(_ref, () => (methods));
// Here ref instead of childRef
return <div ref={ref}> {children} </div>
});
But really I don't quite get why you would need ChildWithForwardRef at all. The code is basically equivalent to this simpler version:
const Box: React.FC<BoxProps> = ({ children, ...rest }: BoxProps): JSX.Element => {
const childRef = useRef<HTMLDivElement>();
const showWidth = () => {
if(childRef.current) {
console.log("childRef.current is present...");
React.Children.forEach(children, item => console.log(item))
console.log("offsetWidth = " + childRef.current.offsetWidth);
} else {
console.log("childRef.current is UNDEFINED");
}
}
return (
<div className={'BoxArea'}>
<button name="ChildComp" onClick={showWidth}>get Width</button>
<div ref={childRef}>{children}</div>
</div>
);
}
You can't solve this completely with React. I solved it by wrapping the child component, making it take the form of the parent.

Set React Context inside function-only component

My goal is very simple. I am just looking to set my react context from within a reusable function-only (stateless?) react component.
When this reusable function gets called it will set the context (state inside) to values i provide. The problem is of course you can't import react inside a function-only component and hence I cannot set the context throughout my app.
There's nothing really to show its a simple problem.
But just in case:
<button onCLick={() => PlaySong()}></button>
export function PlaySong() {
const {currentSong, setCurrentSong} = useContext(StoreContext) //cannot call useContext in this component
}
If i use a regular react component, i cannot call this function onClick:
export default function PlaySong() {
const {currentSong, setCurrentSong} = useContext(StoreContext) //fine
}
But:
<button onCLick={() => <PlaySong />}></button> //not an executable function
One solution: I know i can easily solve this problem by simply creating a Playbtn component and place that in every song so it plays the song. The problem with this approach is that i am using a react-player library so i cannot place a Playbtn component in there...
You're so close! You just need to define the callback inside the function component.
export const PlaySongButton = ({...props}) => {
const {setCurrentSong} = useContext(StoreContext);
const playSong = () => {
setCurrentSong("some song");
}
return (
<button
{...props}
onClick={() => playSong()}
/>
)
}
If you want greater re-usability, you can create custom hooks to consume your context. Of course where you use these still has to follow the rules of hooks.
export const useSetCurrentSong = (song) => {
const {setCurrentSong} = useContext(StoreContext);
setCurrentSong(song);
}
It is possible to trigger a hook function by rendering a component, but you cannot call a component like you are trying to do.
const PlaySong = () => {
const {setCurrentSong} = useContext(StoreContext);
useEffect( () => {
setCurrentSong("some song");
}, []
}
return null;
}
const MyComponent = () => {
const [shouldPlay, setShouldPlay] = useState(false);
return (
<>
<button onClick={() => setShouldPlay(true)}>Play</button>
{shouldPlay && <PlaySong />}
</>
)
}

How to test if component hast only the allowed props and uses only the allowed classes with Jest?

I have a Button component that looks like this:
const Button = ({
children,
type,
btnStyles,
onClick,
}: any) => {
//...
}
export default Button
I wan't to make sure that the button is only used with the allowed props defined above. My test currently looks like this:
it('should only have the allowed props', () => {
const tree = shallow(
<Button
type='button'
buttonStyles='a-custom-button'
onClick={() => {
console.log('Custom Button Clicked')
}}
>
<i></i>
Button
</Button>
)
expect(tree.prop('type')).toBeDefined()
expect(tree.prop('buttonStyles')).toBeDefined()
})
I also want to make sure that only allowed class names can be used for buttonStyles. For example the button can only contain the classes .a-custom-button and .a-custom-button-styles.
How can I do this with Jest?
#Clarity is correct. You're using TypeScript so you could use a union of valid class names:
type ButtonProps = {
btnStyles: 'a-custom-button' | 'a-custom-button-styles';
}
const Button = ({
btnStyles,
}: ButtonProps) => {
console.log(btnStyles);
return null;
}
Button({ btnStyles: 'a-custom-button' }) // works
Button({ btnStyles: 'a-custom-button-styles' }) // also works
Button({ btnStyles: 'invalid-class-name' }) // doesn't work - invalid prop value in TypeScript
Playground:
https://www.typescriptlang.org/play?#code/C4TwDgpgBAQgrsYB7AdgBQE5LAZygXigG8AoKKAI2BQGVQAbCHALigHIBDAWgGM4dkAWy4UEyFGygAfdtz4Ckw0YlRcBIRjjYBuEgF8SJHqgGwxqAlAAUpcuSq0GTADT7W8Feiy4AlAQB8xGTkxig4SIwAdPRIAOZWDnQaTD66dhgQwHAYKFAocPT0ugYkHuI2lNRJmqycvPxCIuYSUHp+dh0A9J1QAO5IGADWOKXNFYlOLLL1CkrNapOSbVDdUBz04X0Dw6Oe41WTtQCWKABu60cAJrz0HDg4XCgcghBL7XarJ+f0V1Bg3lBvnBoAAVcAQGg8DBHMDAKAQDBYDAkIA

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