I have this project structure
Sorry for question, I am new in React, I can't uderstand how I should call this code in ol-map.js
import React from "react";
import {
Map,
layer,
Layers
} from "react-openlayers";
class olMap extends React.Component {
render() {
return (
<div className="Map">
<Map view={{ center: [0, 0], zoom: 2 }}>
<Layers>
<layer.Tile />
</Layers>
</Map>
</div>
);
}
}
export default olMap;
in my Map.js page?
import React, {Component} from 'react';
import olMap from '../components/map/ol-test3/ol-map';
class Map extends Component {
render() {
return (
<olMap/>
);
}
}
export default Map;
P.S. This is index.js file and I have no idea why I need it.
import React from "react";
import ReactDOM from "react-dom";
import olMap from "./ol-map";
const rootElement = document.getElementById("root");
ReactDOM.render(
<React.StrictMode>
<olMap />
</React.StrictMode>,
rootElement
);
In your component .js, make sure you have
import React, { Component } from "react";
class OLMap extends Component {
And then
import OLMap from "./OLMap";
And of course check your folder structure
import OLMap from "../map/ol-test3/ol-map"
Name does not matter in default export so you can name whatever you want while importing.
Related
I've created a simple test program in React which displays a piece of text.
import React from 'react';
import componentClass from './components/componentClass';
export default function App () {
return (
<h1>example</h1>
)
}
What I'm trying to do now is take this example text and make it its own separate component. I've created a class component named componentClass where the example text is displayed.
import React, { Component } from 'react';
export default class componentClass extends Component {
render() {
return (
<h1>example</h1>
)
}
}
I'm then rendering this component in App.js.
import React from 'react';
import componentClass from './components/componentClass';
export default function App () {
return (
<componentClass />
)
}
The problem is that nothing is showing up so I'm confused as to why the component isn't being displayed. Below is my index.js file.
import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import reportWebVitals from './reportWebVitals';
ReactDOM.render(
<React.StrictMode>
<App />
</React.StrictMode>,
document.getElementById('root')
);
reportWebVitals();
You should be using PascalCase when naming React components
working fiddle
class ComponentClass extends React.Component {
render() {
return (
<h1>Component class</h1>
)
}
}
function App () {
return (
<ComponentClass />
)
}
ReactDOM.render(<App />, document.querySelector("#app"))
In React, ALl components should have the first letter capitalized which means you need to edit each time you mentioned componentClass and turn it into ComponentClass
Try wrapping your return in a react fragment like so:
return (
<>
<ComponentClass />
</>
)
Tried to transfer data from 2 components to one using the same method, but it is working only for 50%. There are 3 documents: App.js, Hort.js, Hord.js. Transfering from app.js to hort.js is working, but from hord.js to hort.js isn't. What could be the reason?
App.js:
import React from 'react'
import Hort from './Hort'
function App(props) {
const text1 = 'check1'
return (
<Hort test1={text1} />
);
}
export default App;
Hord.js:
import React from 'react'
import Hort from './Hort'
function Hord(props) {
const text2 = 'check2'
return (
<Hort test2={text2} />
);
}
export default Hord;
Hort.js:
import React from 'react'
import App from './App'
import Hord from './Hord'
function Hort(props) {
return (
<div>
<h1>Just {props.test1}</h1>
<h2>Just {props.test2}</h2>
</div>
)
}
export default Hort;
You are never rendering <Hord>, if a component is never rendered, it won't render what's inside it.
In your index.js, you probably have code that looks like this:
import { StrictMode } from "react";
import ReactDOM from "react-dom";
import App from "./App";
const rootElement = document.getElementById("root");
ReactDOM.render(
<StrictMode>
<App />
</StrictMode>,
rootElement
);
This code indicates that the <App> component will get rendered in the root element from your index.html.
So starting from the <App> component, you can build your component tree, because you never call <Hord>, it will never render, nor will the components rendered inside <Hord>.
Render <Hord> inside your <App> component.
import React from 'react'
import Hort from './Hort'
import Hord from './Hord'
function App(props) {
const text1 = 'check1'
return (
<Hort test1={text1} />
<Hord />
);
}
export default App;
As mentioned in the comments, you shouldn't import components that could cause infinite loops.
import React from 'react'
// * removed imports
function Hort(props) {
return (
<div>
<h1>Just {props.test1}</h1>
<h2>Just {props.test2}</h2>
</div>
)
}
export default Hort;
I'm getting this error:
Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.
Check the render method of App.
Here's my App.js code:
import React, { Component } from 'react';
import Particles from 'react-particles-js';
import Clarifai from 'clarifai';
import './App.css';
import Navigation from './Components/Navigation/Navigation';
import Logo from './Components/Logo/Logo';
import Imagelinkform from './Components/Imagelinkform/Imagelinkform';
import Rank from './Components/Rank/Rank'
import Facerecog from './Components/Facerecog/Facerecog';
const app = new Clarifai.App({
apiKey: '391e77688a1e40ceaf6264a70543fcc5'
});
const particlesOptions={
particles: {
number:{
value:30,
density:{
enable:true,
value_area:800
}
}
}
}
class App extends Component {
constructor(){
super();
this.state={
input:'',
imageUrl:''
}
}
onInputChange=(event)=>{
console.log(event.target.value);
}
onButtonSubmit=()=>{
this.setState({imageUrl: this.state.input});
app.models
.predict(
Clarifai.FACE_DETECT_MODEL,
this.state.input)
.then(
function(response){
console.log(response.outputs[0].data.region[0].region_info.bounding_box)
},
function(err){
}
)
}
render(){
return (
<div className="App">
<Particles className='particles'
params={particlesOptions}
/>
<Navigation/>
<Logo />
<Rank />
<Imagelinkform onInputChange={this.onInputChange} onButtonSubmit={this.onButtonSubmit}/>
<Facerecog imageUrl={this.state.imageUrl} />
</div>
);
}
}
export default App;
index.js:
import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import reportWebVitals from './reportWebVitals';
import 'tachyons';
ReactDOM.render(
<App />,
document.getElementById('root'));
reportWebVitals();
This is caused by export and import of JS files in your App.js. Make sure you're doing something like in this your app
// SomeFile.js
const SomeFile = () => {
....
....
}
export default SomeFile //Default Export
Now in your App.js
import SomeFile from './SomeFile' // Correct Way
import {SomeFile} from './SomeFile' // Wrong way for default import
An image from here for better understanding
Hello i want to pass props from index.html to App.tsx as you see i'm using typescript. so i want to do it with typescript.
my code
//index.html
<div id="root" name="test"></div> //props name test
//Index.tsx
import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';
var container =document.getElementById('root');
ReactDOM.render(
<App name={container.getAttribute('name')} />
,
container
);
serviceWorker.unregister();
//i'm sorry i should have provided this my knowledge about typescript is very low
//App.tsx
import React from 'react';
import logo from './logo.svg';
import './App.css';
class App extends React.Component {
render(){
return (
<div className="App">
<p>{this.props.name}</p>
</div>
)
}
}
export default App;
You should add props to your App component constructor:
class App extends React.Component {
constructor(props) {
super(props);
}
render(){
Embarrassing question, but here we go.
I have a layout.js file that is supposed to render out my React components.
Layout.j:s
import React, { Component } from 'react'
import MainNavbar from './Navbar'
import AddButton from './AddButton'
export default class Layout extends Component {
render() {
return (
<div>
<Navbar />
<AddButton />
</div>
)
}
}
The Navbar component works fine, but my AddButton wont display at all. I've tried console.log-ging from it and nothing gets outputted in the console. So I guess my problem has to do with my component not getting linked.
Here's the file that won't get displayed:
AddButton.js:
import React, { Component } from 'react'
import { Button } from 'react-bootstrap'
export default class AddButton extends Component {
render() {
console.log('hejsan')
return (
<div>
helloooooo
</div>
)
}
}
Here is the index.js file:
index.js
import React, { Component } from 'react'
import ReactDOM from 'react-dom'
import './index.css'
import Layout from './components/Navbar'
const app = document.getElementById('root')
ReactDOM.render(<Layout />, app)
I bet my problem is super basic, but I have no idea how to resolve this.
Thanks for reading!
So the mistake is very basic, you have imported Layout from Navbar which is nothing but your Navbar component and hence only Navbar is rendered, rather you should have imported it from Layout.js
import React, { Component } from 'react'
import ReactDOM from 'react-dom'
import './index.css'
import Layout from './components/Layout'
const app = document.getElementById('root')
ReactDOM.render(<Layout />, app)
Also in Layout.js change
import MainNavbar from './Navbar'
to
import Navbar from './Navbar'