i'm trying to render a useHook statement in React that just display the length of the array and nothing getting render.
Here is APP.js
import React, { useState } from 'react'
import TodoList from './TodoList'
function App() {
const [todos, setTodos] = useState(['test1', 'test2'])
return (
<>
<TodoList todos={todos} />
<input type="text" />
<button>Add Todo</button>
<button>Clear Completed Todos</button>
<div>0 left to do</div>
</>
)
}
export default App;
Here TodoList.js
import React from 'react'
export default function TodoList(todos) {
return (
<div>
{todos.length}
</div>
)
}
Here index.js
import React from 'react';
import ReactDOM from 'react-dom/client';
import App from './App';
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(
<React.StrictMode>
<App />
</React.StrictMode>
);
Screenshot of what getting render
screenshot
Change the TodoList Component to this,
import React from 'react'
export default function TodoList({todos}) {
return
<div>
{todos.length}
</div>
)
or
import React from 'react'
export default function TodoList(props) {
return (
<div>
{props.todos.length}
</div>
)
Just remember you receive props in the form of an object, so you can either de-structure it or use dot notation or bracket notation to access the peops you pass to a component
Related
Hi I'm creating a Teams App and im having trouble implementing a DatePicker in one of my screen.
My basic test screen:
import React from "react";
import DatePicker from "react-datepicker";
import "react-datepicker/dist/react-datepicker.css";
export default function TestScreen() {
let [selectedDate, setSelectedDate] = useState("");
return(
<div>
<h1>TEST SCREEN</h1>
<div>
<DatePicker
selected={selectedDate}
onChange={date => setSelectedDate(date)}
/>
</div>
</div>
)
}
the tab component:
import React from "react";
// https://fluentsite.z22.web.core.windows.net/quick-start
import { Provider, teamsTheme } from "#fluentui/react-northstar";
import { HashRouter as Router, Redirect, Route } from "react-router-dom";
import Tab from "./Tab";
import "./App.css";
import { useTeams } from "#microsoft/teamsfx-react";
import "bootstrap/dist/css/bootstrap.min.css"
import TestScreen from "./screens/test";
export default function App() {
const { theme } = useTeams({})[0];
return (
<Provider theme={theme || teamsTheme} styles={{ backgroundColor: "#eeeeee" }}>
<Router>
<TestScreen />
</Router>
</Provider>
);
}
[The error I get][1]
[1]: https://i.stack.imgur.com/Sc7cX.png
For those wondering, I fixed my issue replacing the by a simple . Not the solution i wanted to use at first but at least it's working fine. Might be a compatibility issue between Teams toolkit, React and some packages..
I see you haven't imported useState in your file. Also add current date as the default value of the selectedDate state. Try this
import React, { useState } from "react";
import DatePicker from "react-datepicker";
import "react-datepicker/dist/react-datepicker.css";
export default function TestScreen() {
let [selectedDate, setSelectedDate] = useState(new Date());
return(
<div>
<h1>TEST SCREEN</h1>
<div>
<DatePicker
selected={selectedDate}
onChange={date => setSelectedDate(date)}
/>
</div>
</div>
)
}
In case you're still not able to use it check if you're using an older version of react. Since hooks are supported in React 16.8.0 or higher.
I am not able to use React hooks. I have 4 components:
ComponentA
componentC
componentE
componentF
I need to pass value to componentF directly from componentA without having to pass from componentC and componentE. All components are in a single tree.
// componentA
import React from 'react';
import './App.css';
import ComponentC from "./components/ComponentC";
export const UserContext = React.useContext();
function App() {
return (
<div className="App">
<UserContext.Provider>
<ComponentC value={'My message'}/>
</UserContext.Provider>
</div>
);
}
export default componentA;
// componentF
import React from 'react';
import UserContext from '../App';
function ComponentF() {
return (
<div>
<UserContext.Consumer>
{
user => {
return (
<div>you are {user}</div>
)
}
}
</UserContext.Consumer>
</div>
)
}
export default ComponentF;
It is giving an error when I am trying to use context:
Invalid hook call. Hooks can only be called inside of the body of a function component.
The mistake is that you are using React.useContext()
You should be doing:
export const UserContext = React.createContext();
To pass to the child components of Component A, you can do it like this:
<UserContext.Provider value={100}>
<ComponentC .../>
</UserContext.Provider>
And instead of using UserContext.Consumer, you can get the value using React.useContext inside the component body of ComponentF.
// componentF
import React from 'react';
import {UserContext} from '../App';
function ComponentF() {
const value = React.useContext(UserContext);
return (
<div>
....
{value} // which will be equal to 100
</div>
)
}
export default ComponentF;
Im new to react hooks and are experimenting a bit. I can display my values that are generated in Provider.js in App.js through Comptest.js. My problem is that the structure of my project with css etc makes it inconvenient to have a structure in the App.js like this:
<Provider>
<Comptest />
</Provider>
is it possible to fetch the data without displaying the components in that way in the app? just passing it between the components.
Here is a compact version of my application:
App.js
import React, { useContext } from "react";
import Provider from "./Provider";
import Comptest from "./Comptest";
import DataContext from "./Context";
function App() {
return (
<div className="App">
<h2>My array!</h2>
<Provider>
<Comptest />
</Provider>
</div>
);
}
export default App;
Provider.js
import React, { useState } from "react";
import DataContext from "./Context";
const Provider = props => {
const data = ["item1", "item2"];
return (
<DataContext.Provider value={data}>{props.children}</DataContext.Provider>
);
};
export default Provider;
Comptest.js
import React from "react";
import DataContext from "./Context";
const Comptest = () => {
const content = React.useContext(DataContext);
console.log(content);
return <div>{(content)}</div>;
};
export default Comptest;
Context.js
import React from "react";
const DataContext = React.createContext([]);
export default DataContext;
I am new to the Redux pattern i'm having some trouble linking an action in a separate JS file to it's parent component. Here is the component:
import React, {Component} from 'react';
import {bindActionCreators} from 'redux';
import {connect} from 'react-redux';
import playSample from './sampleActions/clickToPlay';
class SamplesInnerLrg extends Component {
render() {
return <div>
{
this.props.samples.map((sample) => {
return (
<div key={sample.id} className="sample-comp-lge">
<div className="sample-comp-lge-header">
<span className="sample-comp-lge-Name">{sample.sampleName}</span>
<span className="sample-comp-lge-id">{sample.sampleFamily}</span>
</div>
<div className="sample-comp-lge-audio" ref={sample.id} onClick={() => this.bind.playSample(sample)}>
<audio preload="auto" id="myAudio">
<source src={sample.soundSource} type="audio/wav" />
</audio>
</div>
<div className="sample-comp-lge-owner">{sample.uploader}</div>
</div>
)
})
}
</div>
}
}
function mapStateToProps(state) {
return {
samples:state.samples
};
}
function matchDispatchToProps(dispatch) {
return bindActionCreators({playSample:playSample},dispatch)
}
export default connect(mapStateToProps,matchDispatchToProps)(SamplesInnerLrg);
Specifically I am trying to have an onClick action on this line that will call a function in an imported file (clickToPlay.js):
<div className="sample-comp-lge-audio" ref={sample.id} onClick={() => this.bind.playSample(sample)}>
The clickToPlay file looks like so:
import $ from 'jquery';
export const playSample = (sample) => {
console.log(sample);
return {
type:"Play_Sample_clicked",
payload:sample
}
};
the error i'm getting on click is Cannot read property 'playSample' of undefined. I'm guessing I have bound the action to the component correcly but I can't tell why?
EDIT:
Here is my index.js file as requested:
import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';
import {Provider} from 'react-redux';
import { createStore,compose } from 'redux';
import allReducers from './reducers';
const store = createStore(allReducers,compose(
window.devToolsExtension ? window.devToolsExtension() : f => f
));
ReactDOM.render(
<Provider store={store}>
<App />
</Provider>
,
document.getElementById('root')
);
You aren't exporting 'playSample' as the default export, you have two ways to reslove this:
You can do:
import { playSample } from './sampleActions/clickToPlay';
or
you can change export const playSample to const playSample Then add export default playSample at the end of your file.
Another note I want to mention about this line:
return bindActionCreators({playSample:playSample},dispatch)
I don't see why you are doing {playSample:playSample} just change it to playSample. ES6 allows you to eliminate key if it's the same as value, this is called object literal property value shorthand.
I have a code to run app like this:
import React from 'react'
import { render } from 'react-dom'
import AComponent from './components/AComponent'
render(
<AComponent>
<span id="needShow">HTML inner Component Tag</span>
</AComponent>,
document.getElementById('root')
)
And this is component code:
import React from 'react'
const AComponent = () => (
<div>
<span> Hello of AComponent</span>
</div>
)
export default AComponent
How can I show span with the id needShow?
Child components are passed to a component via the children prop:
const AComponent = (props) => (
<div>
{props.children}
</div>
);