Develop Reference

Change the state of arrows in a dropdown list

The code below illustrates a normal drop down list. To indicate a drop down list, I use a down arrow with
arrow_drop_down
This arrow remains static for me in any state of the list (open or closed). However, I would like that when clicking on the list, the arrow changes to
arrow_drop_up
.
Those. so that with two different states of the list, there would be two different arrows.
export default function FilterStatusCode() {
const [values, setValues] = React.useState([]);
const [isExpanded, setIsExpanded] = useState(false);
const toggleExpand = () => {
setIsExpanded(!isExpanded);
};
return <>
<div className="item-toggle-statuscode" onClick={toggleExpand}>
<h6>Status Code</h6>
<span class="material-icons">
arrow_drop_down
</span>
</div>
{ isExpanded &&
<div>
<TagInput
inputProps={{ placeholder: 'Add status code...' }}
values={values}
onChange={(values) => {
setValues(values)}}>
</TagInput>
</div>
}
</>;
}

try
<div className="item-toggle-statuscode" onClick={toggleExpand}>
<h6>Status Code</h6>
<span class="material-icons">
{ isExpanded ? arrow_drop_up : arrow_drop_down }
</span>
</div>

You can choose which arrow you use depending on the current state:
// If the list is open show the `up` arrow
// otherwise show the `down` arrow
<span className={open ? "up" : "down"}></span>
I had to improvise in this example and used unicode in the class names.
const { useState } = React;
function Example() {
return (
<div>
<Item />
<Item />
</div>
);
}
function Item() {
const [ input, setInput ] = useState('');
const [ open, setOpen ] = useState(false);
function handleChange(e) {
setInput(e.target.value);
}
function handleOpen() {
setOpen(!open);
}
function handleClick() {
console.log(input);
}
return (
<div className="item">
<div onClick={handleOpen} className="heading">
<span>Status code</span>
<span className={open ? "up" : "down"}></span>
</div>
{open && (
<div>
<input
type="text"
onChange={handleChange}
value={input}
/>
<button
type="button"
onClick={handleClick}
>Submit
</button>
</div>
)}
</div>
);
}
ReactDOM.render(
<Example />,
document.getElementById('react')
);
.down:after { content: '\25BC'; }
.up:after { content: '\25B2'; }
.heading:hover { cursor: pointer; color: red; }
.item { margin-bottom: 1em; }
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.2/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.2/umd/react-dom.production.min.js"></script>
<div id="react"></div>
Additional documentation
Conditional (ternary) operator

Hiding and showing content on click using React

In a nutshell, i am creating a case study for a potential job, the employer wants me to use a React app to create it...
I want to create a button that has the start function that:
Hides original content
displays the hidden content,
i got the hidden content to show but the original content is still visible, any help?
my code below:
import React, { useState } from 'react'
function Body() {
const [show, setShow] = useState(true);
const [hide, setHidden] = useState(true);
return (
<>
<div className='container'>
<div className="start-container">
<h2>Click Start To View The Application</h2>
<button onClick={ () => setShow(s => ! s) } className='btn'>Start!</button>
</div>
{/* URL Link Input */}
<div>
{!show ? <form action="GET">
<input type="text" />
<button className='btn'>Submit</button>
</form> : null }
</div>
</div>
</>
)
}
export default Body

You are close, you need to have the original content in the ternary so it's hidden once you toggle show. I also changed setShow to set show to false rather than the previous value since it doesn't matter because the button is not toggable because once you click it and can't re toggle the original content.
import React, { useState } from 'react'
function Body() {
const [show, setShow] = useState(true);
return (
<div className='container'>
{show ? (
<div className="start-container">
<h2>Click Start To View The Application</h2>
<button onClick={() => setShow(false)} className='btn'>Start!</button>
</div>
) : (
<form action="GET">
<input type="text" />
<button className='btn'>Submit</button>
</form>
)
</div>
)
}
export default Body

it dose not need hide state and you can toggle visibility just with show state. try this:
{ show ? <form action="GET">
<input type="text" />
<button className='btn'>Submit</button>
</form> : null
}

This should work.
import React, { useState } from 'react';
function Body() {
const [show, setShow] = useState(false);
return (
<>
<div className="container">
{/* URL Link Input */}
<div>
{show ? (
<form action="GET">
<input type="text" />
<button className="btn">Submit</button>
</form>
) : (
<div className="start-container">
<h2>Click Start To View The Application</h2>
<button onClick={() => setShow(!show)} className="btn">
Start!
</button>
</div>
)}
</div>
</div>
</>
);
}
export default Body;

You could use an appStarted state and then render your component conditionnally:
const { useState } = React
function Body() {
const [appStarted, setAppStarted] = useState(false)
return (
<div className="container">
{appStarted ? (
<div>
<h2>Hidden Content</h2>
</div>
) : (
<div className="start-container">
<h2>Click Start To View The Application</h2>
<button onClick={ () => setAppStarted(true) } className='btn'>Start!</button>
</div>
)}
</div>
)
}
ReactDOM.render(<Body />, document.getElementById("root"))
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.2/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.2/umd/react-dom.production.min.js"></script>
<div id="root"></div>

OnChange method does not work when trying to get text from input - reactjs

I am developing a chat and the problem I am having has to do with creating a new chat. When clicking on the button to create a new chat, a popup appears with the chat name field to fill in. However, when I click on "Create Now" I can't get the input text.
I've tried adding value = {nameChat} but this way I can't write to the input. Nothing appears. I also tested defaultValue = {nameChat} but it doesn't work either.
If anyone could help me, I would appreciate it.
Popup to create new chat
import { confirmAlert } from 'react-confirm-alert'; // Import
import 'react-confirm-alert/src/react-confirm-alert.css' // Import css
import { useState } from 'react'
const HeaderChats = ({ onAddNewChat }) => {
var [chatName, setChatName] = useState('');
const onSubmit = (e) => {
e.preventDefault()
if (!chatName) {
alert('Please write the name of the chat!')
console.log("Nome -> " + chatName)
return
}
console.log(chatName)
onAddNewChat(chatName)
setChatName('')
}
function createChat() {
confirmAlert({
customUI: ({ onClose }) => {
return (
<div className='custom-ui'>
<h1>Create new chat</h1>
<form style={{resize: "vertical"}} onSubmit={onSubmit}>
<label className="cname-label">Chat Name</label>
<input className="cname-input" type='text' placeholder="Type the name of the chat..." onChange={(e) => setChatName(e.target.value)} value={chatName}/>
<button className="cancel-button" onClick={onClose}>Cancel</button>
<button className="submit-new-chat-button" type='submit'>Create now</button>
</form>
</div>
)
}
})
}
return (
<div className="header-left">
<div className="header-left-column-left">
<HiMenu className="icon" size={25} style={{ color: "#b3c5d3" }} />
</div>
<div className="header-left-column-right">
<input className="input-search" type="text" placeholder="Pesquisar conversa..." />
<MdAddCircleOutline className="button-new-message" size={25} style={{ color: "#dca297" }} onClick={() => createChat()} /> </div>
</div>
);
}

Because once the confirmAlert is created, the submit function will not be changed. So to avoid this, you need to render the chat as a component.
function Chat(props){
var [chatName, setChatName] = useState("");
const onSubmit = useCallback((e) => {
e.preventDefault();
if (!chatName) {
alert("Please write the name of the chat!");
return;
}
alert(chatName);
setChatName("");
}, [chatName]);
return <div className="custom-ui">
<h1>Create new chat</h1>
<form style={{ resize: "vertical" }} onSubmit={onSubmit}>
<label className="cname-label">Chat Name</label>
<input
className="cname-input"
type="text"
placeholder="Type the name of the chat..."
onChange={(e) => setChatName(e.target.value)}
/>
<button className="cancel-button" onClick={props.onClose}>
Cancel
</button>
<button className="submit-new-chat-button" type="submit">
Create now
</button>
</form>
</div>
}
function App() {
function createChat() {
confirmAlert({
customUI: ({ onClose }) => {
return (
<Chat onClose={onClose}/>
);
}
});
}
return (
<div className="header-left">
<MdAddCircleOutline
className="button-new-message"
size={25}
style={{ color: "#dca297" }}
onClick={() => createChat()}
/>{" "}
</div>
);
}

You should remove onSubmit in form element and also remove type="submit" on button change it to onClick={onSubmit}
<div className="custom-ui">
<h1>Create new chat</h1>
<form style={{ resize: "vertical" }} >
<label className="cname-label">Chat Name</label>
<input
className="cname-input"
type="text"
placeholder="Type the name of the chat..."
onChange={(e) =>
{
setChatName(e.currentTarget.value)}
}
/>
<button className="cancel-button" onClick={onClose}>
Cancel
</button>
<button className="submit-new-chat-button" onClick={onSubmit}>
Create now
</button>
</form>
</div>

How to totally disable a react component?

I have a react component which has some buttons and text inputs. I want to totally disable all the things inside this component until some other works are complete. How to make the entire inner component disabled?

You can add disabled props and use CSS to disable div
const MyComponent = ({disabled}) => {
return (
<div style={disabled ? {pointerEvents: "none", opacity: "0.4"} : {}}>
<h1> Text</h1>
<input type="text"/>
<input type="password"/>
<button>Login</button>
</div>
)
}

Better to use form and fieldset, and put all the input/button elements inside that. You can disable all of them by setting the property disabled to fieldset.
Refer MDN Doc for more details.
Working example:
class App extends React.Component {
constructor () {
super()
this.state = { disable: false }
}
toggleDisable = () => this.setState(prevState => ({disable: !prevState.disable}))
buttonClick = (e) => {
e.preventDefault();
console.log('button clicked');
}
render (){
return (
<div>
<button className='toggle' onClick={this.toggleDisable}>Toggle Disable</button>
<form>
<fieldset disabled={this.state.disable}>
<input />
<button onClick={this.buttonClick}>Button</button>
</fieldset>
</form>
</div>
)
}
}
ReactDOM.render(<App />, document.getElementById('app'))
.toggle {
margin-bottom: 20px;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<div id='app' />

All you need to do is add a disabled prop on the component and pass it on to the inner fields like
<MyComponent disabled={shouldComponentBeDisabled} {...otherProps} />
and in implementation
const MyComponent = ({disabled}) => {
return <div>
<button disabled={disabled}>someBtn</button>
<input type="text" disabled={disabled}/>
</div>
}

You can use disabled prop pattern to save the day.
const App = () => {
return (
<div>
<SomeComponent disabled />
</div>
);
};
const SomeComponent = ({ disabled = false }) => {
return (
!disabled && (
<div>
<h2>Disable SomeComponent to see magic happen!</h2>
</div>
)
);
};

Dynamically adding button to div ReactJS?

Ok so here's my code:
import React, { Component } from 'react';
import logo from './logo.svg';
import './App.css';
var uuid = require("uuid-v4");
// Generate a new UUID
var myUUID = uuid();
// Validate a UUID as proper V4 format
uuid.isUUID(myUUID); // true
var questionNum = 0;
class App extends Component {
constructor(props) {
super(props);
this.state = {
key: uuid(),
title: "",
author: "",
questions: [],
answers: []
};
this.handleChange = this.handleChange.bind(this);
this.addQuestion = this.addQuestion.bind(this);
this.removeItem = this.removeItem.bind(this)
}
componentDidMount() {
// componentDidMount() is a React lifecycle method
this.addQuestion();
}
handleChange(event) {
const target = event.target;
const value = target.type === "checkbox" ? target.checked : target.value;
const name = target.name;
this.setState({
[name]: value
});
}
removeItem (index) {
questionNum--;
this.setState(({ questions }) => {
const mQuestions = [ ...questions ]
mQuestions.splice(index, 1)
return { questions: mQuestions }
})
this.setState(({ answers }) => {
const mAnswers = [ ...answers]
mAnswers.splice(index, 4)
return { answers: mAnswers}
})
console.log(
"answers",
this.state.answers,
"questions",
this.state.questions,
questionNum,
this.state.title,
this.state.author
);
}
addQuestion() {
questionNum++;
this.setState(previousState => {
const questions = [
...previousState.questions,
<input
type="text"
onChange={this.handleChange}
name="question"
key={uuid()}
/>
];
const answers = [
...previousState.answers,
];
for (var i = 0; i < 4; i++) {
answers.push(
<input
type="checkbox"
name={uuid()}>
<input
type="text"
onChange={this.handleChange}
name={uuid()}
/>
</input>
);
}
return { questions, answers };
});
console.log(
"answers",
this.state.answers,
"questions",
this.state.questions,
questionNum,
this.state.title,
this.state.author
);
}
render() {
return (
<div className="App">
<div>
<header className="App-header">
<img src={logo} className="App-logo" alt="logo" />
<h1 className="App-title">Quiz Form 3.0</h1>
</header>
<p className="App-intro">
To get started, edit <code>src/App.js</code> and save to reload.
</p>
</div>
<div className="formDiv">
<form>
<div className="Intro">
Give your Quiz a title:{" "}
<input
type="text"
value={this.state.title}
onChange={this.handleChange}
name="title"
/>
<br />
Who's the Author?{" "}
<input
type="text"
value={this.state.author}
onChange={this.handleChange}
name="author"
/>
<br />
<br />
</div>
<div className="questions">
<div className="questions">
Now let's add some questions... <br />
<ol>
{this.state.questions.map(question => {
return (
<li>
<div key={uuid()}>
Question
{question}<br />
Answer Choices<br />
{Array.from({ length: 4 }, () => (
<input type="text" key={uuid()} onChange={this.handleChange} />
))}
</div>
</li>
);
})}
</ol>
</div>
{
// This is what it would look like for the structure
// I proposed earlier.
// this.state.questions.map((question) {
// return (
// <div>{question.quesion}</div>
// {
// question.answers.map((answer) => {
// return (<div>{answer}</div>);
// })
// }
// );
// })
// This would output all questions and answers.
}
</div>
</form>
<button id="addQuestionButton" onClick={this.addQuestion}>Add Question</button>
{ this.state.questions.map((question, index) => {
return <button key={uuid()} onClick={ () => this.removeItem(index) }>Remove Question</button>
}) }
</div>
</div>
);
}
}
export default App;
Ok so here's a link to a quick video demonstrating what it does as of now. In the video you can see the Remove Question buttons that are created (at the bottom of the form) each time a question is added. I would like to have each question's Remove Question button be next to it/in the same div. I'm not entirely sure how I would go about doing this. Any thoughts?
UPDATE: Ok so I have put the buttons inside of the same div with the actual question, but I realized that i am adding a button for each object in the array. Which means that when a question is added a button to remove it is added to every question on the form. I need to make it so it does not .map this. I'm not entirely sure what other function I will do for this, maybe I don't even need a function. I will try my best to work it out. Here's the updated code (some of it):
<div className="questions">
Now let's add some questions... <br />
<ol>
{this.state.questions.map(question => {
return (
<li>
<div key={uuid()}>
Question
{question}<br />
{
this.state.questions.map((question, index) => {
return <button key={uuid()} onClick={ () => this.removeItem(index) }>Remove Question</button>
})
}
Answer Choices<br />
{Array.from({ length: 4 }, () => (
<div>
<input type="checkbox" />
<input type="text" key={uuid()} onChange={this.handleChange} />
</div>
))}
</div>
</li>
);
})}
</ol>
</div>

Something like this...
<ol>
{this.state.questions.map((question, index) => {
return (
<li>
<div key={uuid()}>
Question
{question}<br />
<button onClick={ () => this.removeItem(index) }>
Remove Question
</button>
Answer Choices<br />
{Array.from({ length: 4 }, () => (
<div key={uuid()}>
<input type="checkbox" />
<input type="text" onChange={this.handleChange} />
</div>
))}
</div>
</li>
);
})}
</ol>