My Component isn't conditionally rendering properly - reactjs

I have a simple react page so far where I just have a home component which seems to work fine it is made up from the code I have included what I am trying to do is to render another component the main component when the button that is part of the home component is clicked but it keeps giving me the error and I have no idea what I am doing wrong in this case I have included code for all of my files the main component isn't fully finished right now it was just to test what I am currently doing that I added a paragraph placeholder any help is appreciated thanks
Error: Unknown error
(/node_modules/react-dom/cjs/react-dom.development.js:3994) !The above
error occurred in the component: at Main (exe1.bundle.js:94:3)
at div at App (exe1.bundle.js:31:52) Consider adding an error boundary
to your tree to customize error handling behavior. Visit
https://reactjs.org/link/error-boundaries to learn more about error
boundaries. !Error: Unknown error
Home Component:
import React from "react";
export default function Home(props) {
return (
<main className="home-main">
<div className="content-container">
<div className="bottom-corner">
</div>
<div className="top-corner">
</div>
<h1 className="home-heading">Quizzical</h1>
<p className="home-description">Some description if needed</p>
<button
className="start-button"
onClick={props.handleClick}
>Start quiz
</button>
</div>
</main>
)
}
Main Component:
import react from "react";
export default function Main() {
return (
<h1>hello </h1>
)
}
App:
import React from "react";
import Main from "./components/Main"
import Home from "./components/Home"
export default function App() {
const [startQuiz, setStartQuiz] = React.useState(false);
function clickStart() {
// flip the state on each click of the button
console.log(startQuiz);
setStartQuiz(prevState => !prevState);
}
return (
<div>
{console.log("start", startQuiz)}
{startQuiz ?
<Main />
:
<Home handleClick={clickStart}/> }
}
</div>
)
}
Index:
import React from "react"
import ReactDOM from "react-dom"
import App from "./App";
ReactDOM.render(<App />, document.getElementById("root"))

I think you just have a typo here
import react from "react";
should be
import React from "react";

You can try changing your setStartQuiz to just simply negate the current startQuiz value instead of using prevState.
function clickStart() {
// flip the state on each click of the button
console.log(startQuiz);
setStartQuiz(!startQuiz);
}

Here's a working example based on your code.
code sandbox
import React, { useState } from "react";
const Main = () => <h1>hello </h1>;
const Home = (props) => {
return (
<main className="home-main">
<div className="content-container">
<div className="bottom-corner"></div>
<div className="top-corner"></div>
<h1 className="home-heading">Quizzical</h1>
<p className="home-description">Some description if needed</p>
<button className="start-button" onClick={props.handleClick}>
Start quiz
</button>
</div>
</main>
);
};
export default function App() {
const [startQuiz, setStartQuiz] = useState(false);
return (
<div>
{startQuiz && <Main />}
{!startQuiz && <Home handleClick={() => setStartQuiz(true)} />}
</div>
);
}

Related

Image not getting displayed in react project

This is my App.js. Here, I call the "Profile" Component.
import './App.css';
import Profile from "./Profile"
function App() {
return (
<div className="App">
<Profile />
</div>
);
}
export default App;
Then, inside Profile.js, I call Card component and inside the Card component, I've enclosed an image.
import React from 'react'
import Card from './Card'
import styles from "./Profile.module.css"
import image1 from "./assets/profile1.png"
const Profile = () => {
return (
<Card>
<div>
<img src={image1} alt="" />
</div>
</Card>
)
}
export default Profile
Inside of Card component, I've just applied some CSS to make it look like a Card.
import React from 'react'
import styles from "./Card.module.css"
const Card = () => {
return (
<div className={styles.card}>
</div>
)
}export default Card
This is my folder structure.
I'm really confused why the image isn't getting showed up. Currently this is the output I'm getting.
I've restarted the server as well. But it's not getting fixed.
your card doesn't have a child component return maybe that could be the problem
import React from 'react'
import styles from "./Card.module.css"
const Card = ({children}) => {
return (
<div className={styles.card}>
{children}
</div>
)
}
export default Card
try this

React & Typescript Issue: trigger elements with InsertionObserver using props and manage them in other component

Small premise: I'm not a great Typescript expert
Hi everyone, I'm working on my personal site, I decided to develop it in Typescript to learn the language.
My component tree is composed, as usual, of App.tsx which render the sub-components, in this case Navbar.jsx and Home.jsx.
Below is the App.jsx code:
import './App.css';
import { BrowserRouter as Router, useRoutes } from 'react-router-dom';
import Home from './components/Home';
import Navbar from './components/Navbar';
import { useState } from 'react';
function App(){
const [navbarScroll,setNavbarScrool]=useState(Object)
const handleLocationChange = (navbarScroll : boolean) => {
setNavbarScrool(navbarScroll)
return navbarScroll
}
const AppRoutes = () => {
let routes = useRoutes([
{ path: "/", element: <Home handleLocationChange={handleLocationChange}/> },
{ path: "component2", element: <></> },
]);
return routes;
};
return (
<Router>
<Navbar navbarScroll={navbarScroll}/>
<AppRoutes/>
</Router>
);
}
export default App;
Here, instead, the Home.jsx code:
import { useInView } from 'react-intersection-observer';
import HomeCSS from "../styles/home.module.css"
import mePhoto from "../assets/me.png"
import { useEffect, useState } from 'react';
interface AppProps {
handleLocationChange: (values: any) => boolean;
}
export default function Home(props: AppProps){
const { ref: containerChange , inView: containerChangeIsVisible, entry} = useInView();
useEffect(()=>{
props.handleLocationChange(containerChangeIsVisible)
//returns false at first render as expected
console.log("Home "+containerChangeIsVisible)
},[])
return(
<>
<div className={`${ HomeCSS.container} ${containerChangeIsVisible? HomeCSS.container_variation: ''}`}>
<div className={HomeCSS.container__children}>
{/* when i scroll on the div the css change (this works)*/}
<h1 className={`${ HomeCSS.container__h1} ${containerChangeIsVisible? HomeCSS.container__h1_variation: ''}`}>My<br/> Name</h1>
<p>Computer Science student.</p>
</div>
<img src={mePhoto} className={HomeCSS.image_style}/>
</div>
<div ref={containerChange} style={{height:800,background:"orange"}}>
<p style={{marginTop:20}}>HIII</p>
</div>
</>
)
}
And Navbar.jsx:
import NavbarCSS from "../styles/navbar.module.css"
import acPhoto from "../assets/ac.png"
import { Link } from "react-router-dom";
import { useEffect, useState } from "react";
interface NavbarScroolProp{
navbarScroll:boolean
}
export default function Navbar(props:NavbarScroolProp){
const [scrollState,setScrollState]=useState(false)
const [pVisible,setpVisible] = useState('')
useEffect(()=>{
setTimeout(() => {
setpVisible("")
}, 3000)
setpVisible("100%")
},[])
//returns false also when should be true
console.log(props.navbarScroll)
return (
<>
{/*the props is undefined so the css doesn't change, i need to do this*/}
<nav className={`${props.navbarScroll?NavbarCSS.nav__variation:NavbarCSS.nav}`}>
<div className={NavbarCSS.nav_row}>
<div className={NavbarCSS.nav_row_container}>
<img src={acPhoto} className={NavbarCSS.image_style}/>
<p className={NavbarCSS.p_style} style={{maxWidth: pVisible}}>My name</p>
</div>
<div className={NavbarCSS.nav_row_tagcontainer}>
<Link className={NavbarCSS.nav_row_tag} to="/"> Home</Link>
<Link className={NavbarCSS.nav_row_tag} to="/"> About</Link>
<Link className={NavbarCSS.nav_row_tag} to="/"> Contact</Link>
</div>
</div>
</nav>
</>
);
}
In my application I want to change the background color whenever the div referring to the InsertionObserver ( I use "useInView" hook , from :https://github.com/thebuilder/react-intersection-observer) is displayed. The problem is that the div in question is in the Home.jsx component and I need to change the color of the divs in the navbar as well when the div in Home is triggered(or other components in case I need to in the future).
The question is: How can I dynamically trigger DOM elements of other components (to then perform certain operations) using the InsertionObserver ?
As you can see from the code I tried to create Props, but everything returns undefined and doesn't involve any changes.
I've tried without useEffect, without using the useInView hook, passing the object instead of the boolean value, but I can't find any solutions to this problem.
You would be of great help to me.
PS: I would like to leave the Navbar.jsx component where it is now, so that it is visible in all components.
Any advice or constructive criticism is welcome.

Is it possible to hide a parent component from child component in React.js?

As shown in the Flowchart (Flowchart), I want to hide the Header component if Main component renders the Login component. But if the Main component renders the Home component, I want to display the Header component.
This is App.js file:
import React from 'react'
import Header from 'Header'
import Main from 'Main'
import Footer from 'Footer'
function App() {
return (
<div className="App">
<Header />
<Main />
<Footer />
</div>
)
}
export default App;
This is Main.js file:
import React from 'react'
import Home from './Home'
import Login from './Login'
function Main() {
let user = true //Toggled by users
return (
<div>
{
user ? ( <Home /> ) : ( <Login /> )
}
</div>
)
}
export default Main
Putting the Header Component in Home itself will not solve the problem as I have to add much more pages and adding a Header component in every page doesn't seem efficient.
That's a use case of lifting the state up, here your user state should be in the scope of Header and Main.
Then just pass the user (isLogged in the example) to Main, via props or Context API.
function Main({ isLogged, toggleLogin }) {
return (
<div>
<button onClick={toggleLogin}>toggle</button>
{isLogged ? <>Home</> : <>Login</>}
</div>
);
}
function App() {
const [isLogged, toggle] = useReducer((p) => !p, false);
return (
<div className="App">
{!isLogged && <>Header</>}
<Main isLogged={isLogged} toggleLogin={toggle} />
<>Footer</>
</div>
);
}

how to use react routing to switch between pages

i am currently building a shopping website . i finished the homepage and i have to make routing for other pages
i have 3 main files: App.js, Menuitem.js (which is to execute props), and Homepage.js (which also is used to apply executing props from sections array which includes titles and background images and sections paths)
this is the App js
import React from "react";
import Homepage from './Homepage'
import "./styles.css";
import './Homepage.css'
import {Route, Switch} from "react-router-dom";
const Hatspage=function() {
return(
<div>
<h1>
Hats page
</h1>
</div>
)
}
function App() {
return (
<div>
<Switch>
<Route exact path='/'component={Homepage}/>
<Route path='/hats'component={Hatspage}/>
</Switch>
</div>
);
}
export default App
Menuitem.js
import React from 'react'
import {WithRouter} from 'react'
const Menuitem= function(props){
return(
<div className='card' style={{ backgroundImage: `url(${props.imageUrl})` }} >
<div className='text-frame'>
<h1 className='title'>{props.title}</h1>
<p className='subtitle'>shop now</p>
</div>
</div>
)
}
export default Menuitem
Homepage.js
import React from "react";
import sections from './directory-components';
import Menuitem from "./menu-item-components";
const arrayOne=[sections.slice(0,3)]
const arrayTwo=[sections.slice(3,)]
function extract(item){
return(
<Menuitem
title={item.title} imageUrl={item.imageUrl}/>
)
}
function Homepage(){
return(
<div className='directory-menu'>
<div className='content'>
{sections.slice(0,3).map(extract) }
</div>
<div className='second'>
{sections.slice(3,).map(extract) }
</div>
</div>
)
}
export default Homepage
so i need for example when i click on hats picture i switch to hats page . how to do that
image attached
Thanks in advance
reactjs routing
You can do two different approaches. Both of them will require an extra prop that will be the actual url you want to access when clicking the menu item.
Assuming you modify your section array to look like this:
[{title: 'Your title', imageUrl: 'your-image.jpg', linkUrl: '/hats'}]
And you modify your extract function to add the url value as a prop in the MenuItem component:
function extract(item){
return(
<Menuitem
title={item.title} imageUrl={item.imageUrl} linkUrl={item.linkUrl} />
)
}
You can do this
First one: Using a Link component from react router:
import React from "react";
import { Link } from "react-router-dom";
const Menuitem= function(props){
return(
<Link to={props.linkUrl}>
<div className='card' style={{ backgroundImage: `url(${props.imageUrl})`
}} >
<div className='text-frame'>
<h1 className='title'>{props.title}</h1>
<p className='subtitle'>shop now</p>
</div>
</div>
</Link>
)
}
Now you will have to add extra styling because that will add a regular a tag, but I like this approach because for example you can open the link in a new tab since it is a regular link.
Using the history prop.
import React from "react";
import { useHistory } from "react-router-dom";
const Menuitem= function(props){
const history = useHistory()
const goToPage = () => history.push(props.linkUrl)
return(
<div className='card' style={{ backgroundImage: `url(${props.imageUrl})`
}} onClick={goToPage} >
<div className='text-frame'>
<h1 className='title'>{props.title}</h1>
<p className='subtitle'>shop now</p>
</div>
</div>
)
}
This approach is a basic on click so if you press the component it will go to the selected page, this will work but keep in mind that event bubbling will be harder if you add more on clicks inside the menu item, so please be aware of that.
You should fire an event inside your MenuItem in order to redirect the user
import { useHistory } from 'react-router-dom'
const history = useHistory()
<img onClick={() => history.push('/hats')} />

'signinL' is declared but its value is never read

signinL is declared but never used error, please help, it is an import that I have taken and used as a component still it's showing as error
import React from 'react'
import { Link } from 'react-router-dom'
import signinL from './signinL'
const Navbar = () => {
return (
<nav className="nav-wrapper grey darken-3">
<div className="container">
<Link to='/' className="brand-logo">My Peral</Link>
<signinL />
</div>
</nav>
)
}
export default Navbar

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