It is my understanding that refs are not defined outside the react lifecycle (source). The problem I am trying to solve is to capture a key press at the document level (i.e. trigger the event no matter what element is in focus), and then interact with a react ref. Below is a simplified example of what I am trying to do:
export default class Console extends React.Component {
constructor(props) {
super(props);
this.state = {
visible: false,
text: "",
};
}
print(output: string) {
this.setState({
text: this.state.text + output + "\n"
})
}
toggleVisible()
{
this.setState({visible: !this.state.visible});
}
render() {
const footer_style = {
display: this.state.visible ? "inline" : "none",
};
return (
<footer id="console-footer" className="footer container-fluid fixed-bottom" style={footer_style}>
<div className="row">
<textarea id="console" className="form-control" rows={5} readOnly={true}>{this.state.text}</textarea>
</div>
</footer>
);
}
}
class App extends React.Component {
private console: Console;
constructor() {
super({});
this.console = React.createRef();
}
keyDown = (e) =>
{
this.console.current.toggleVisible(); // <-- this is undefined
}
componentDidMount(){
document.addEventListener("keydown", this.keyDown);
},
componentWillUnmount() {
document.removeEventListener("keydown", this.keyDown);
},
render() {
return (
<div className="App" onKeyDown={this.keyDown}> // <-- this only works when this element is in focus
// other that has access to this.console that will call console.print(...)
<Console ref={this.console} />
</div>
);
}
}
My question is: is there a way to have this sort of document level key press within the lifesycle of react so that the ref is not undefined inside the event handler keyDown? I've seen a lot of solutions that involve setting the tabIndex and hacking to make sure the proper element has focus at the right time, but these do not seem like robust solutions to me.
I'm just learning React so maybe this is a design limitation of React or I am not designing my components properly. But this sort of functionality seems quite basice to me, having the ability to pass components from one to the other and call methods on eachother.
You're calling the onKeyDown callback twice, once on document and once on App.
Events bubble up the tree.
When the textarea is not in focus, only document.onkeydown is called.
When it is in focus, both document.onkeydown and App's div.onkeydown are called, effectively cancelling the effect(toggling state off and back on).
Here's a working example: https://codesandbox.io/s/icy-hooks-8zuy7?file=/src/App.js
import React from "react";
class Console extends React.Component {
constructor(props) {
super(props);
this.state = {
visible: false,
text: ""
};
}
print(output: string) {
this.setState({
text: this.state.text + output + "\n"
});
}
toggleVisible() {
this.setState({ visible: !this.state.visible });
}
render() {
const footer_style = {
display: this.state.visible ? "inline" : "none"
};
return (
<footer
id="console-footer"
className="footer container-fluid fixed-bottom"
style={footer_style}
>
<div className="row">
<textarea id="console" className="form-control" rows={5} readOnly>
{this.state.text}
</textarea>
</div>
</footer>
);
}
}
export default class App extends React.Component {
constructor(props) {
super(props);
this.console = React.createRef();
}
keyDown = (e) => {
this.console.current.toggleVisible(); // <-- this is undefined
};
componentDidMount() {
document.addEventListener("keydown", this.keyDown);
}
componentWillUnmount() {
document.removeEventListener("keydown", this.keyDown);
}
render() {
return (
<div className="App" style={{ backgroundColor: "blueviolet" }}>
enter key to toggle console
<Console ref={this.console} />
</div>
);
}
}
Also, I recommend using react's hooks:
export default App = () => {
const console = React.createRef();
const keyDown = (e) => {
console.current.toggleVisible(); // <-- this is undefined
};
React.useEffect(() => {
// bind onComponentDidMount
document.addEventListener("keydown", keyDown);
// unbind onComponentDidUnmount
return () => document.removeEventListener("keydown", keyDown);
});
return (
<div className="App" style={{ backgroundColor: "blueviolet" }}>
press key to toggle console
<Console ref={console} />
</div>
);
};
I have a component below: there are 2 usecases, when I click on the entire div some function is executed and when I click on just the <img>, some function is executed.
I have 2 props defined, onClick, when clicked on the entire div
and onIconClick when clicked on the img.
export default class List extends React.Component {
onClick() {
this.props.onClick();
}
onIconClick() {
this.props.onIconClick();
}
render() {
return (
<div style="width:200px, height: 200px" onClick={this.onClick.bind(this)}>
<img src="delete.png" onClick={this.onIconClick.bind(this)} />
</div>
);
}
}
here is the way I call the component:
export default class MyApp extends React.Component {
onClick() {
//some execution
}
onIconClick() {
//some other execution
}
render() {
return (
<List
onClick={this.onClick.bind(this)}
onIconClick={this.onIconClick.bind(this)}
/>
);
}
}
Now my issue is the this.onClick.bind(this) gets called all the time even when I click the image, hence I never get to this.onIconClick.bind(this).
I tried reversing the order:
<List onIconClick={this.onIconClick.bind(this)} onClick={this.onClick.bind(this)} />
still doesn't work, not sure what selection criteria I should use in order to distinguish between these 2 clicks.
Any ideas??
Try this:
class Parent extends React.Component {
constructor(props) {
super(props);
this.onClick = this.onClick.bind(this);
this.onIconClick = this.onIconClick.bind(this);
}
onClick() {
alert("Parent-onClick()");
}
onIconClick() {
alert("Parent-onIconClick()");
}
render() {
return (
<div>
<Child onClick={this.onClick} onIconClick={this.onIconClick} />
</div>
);
}
}
class Child extends React.Component {
constructor(props) {
super(props);
this.onClick = this.onClick.bind(this);
this.onIconClick = this.onIconClick.bind(this);
}
onClick() {
this.props.onClick();
}
onIconClick(e) {
e.stopPropagation();
this.props.onIconClick();
}
render() {
let styles = {
height: "500px",
backgroundColor: "blue",
paddingTop: "20px"
};
return (
<div onClick={this.onClick} className="img-wrapper" style={styles}>
<img
onClick={this.onIconClick}
src="https://via.placeholder.com/350x150"
alt="img"
/>
</div>
);
}
}
const rootElement = document.getElementById("root");
ReactDOM.render(<Parent />, rootElement);
<script crossorigin src="https://unpkg.com/react#16/umd/react.development.js"></script>
<script crossorigin src="https://unpkg.com/react-dom#16/umd/react-dom.development.js"></script>
<div id="root"><div>
The idea is using stopPropagation() method of the SyntheticEvent instance.
Your event handlers will be passed instances of SyntheticEvent, a
cross-browser wrapper around the browser’s native event. It has the
same interface as the browser’s native event, including
stopPropagation() and preventDefault(), except the events work
identically across all browsers.
If you find that you need the underlying browser event for some
reason, simply use the nativeEvent attribute to get it.
Using the SyntheticEvent 's methods allows our code to behave exactly the same across all browsers.
You can use e.stopPropagation(). If you want to use e.nativeEvent.stopImmediatePropagation(), you can use in the same line.
onIconClick(e) {
e.stopPropagation();
//e.nativeEvent.stopImmediatePropagation();
this.props.onIconClick();
}
I'm teaching myself react with a super simple app that asks the user to type a word presented in the UI. If user enters it correctly, the app shows another word, and so on.
I've got it almost working, except for one thing: after a word is entered correctly, I need to clear the input element. I've seen several answers here about how an input element can clear itself, but I need to clear it from the component that contains it, because that's where the input is checked...
// the app
class AppComponent extends React.Component {
constructor() {
super();
this.state = {
words: ['alpha', 'bravo', 'charlie'],
index: 0
};
}
renderWordsource() {
const word = this.state.words[this.state.index];
return <WordsourceComponent value={ word } />;
}
renderWordinput() {
return <WordinputComponent id={1} onChange={ this.onChange.bind(this) }/>;
}
onChange(id, value) {
const word = this.state.words[this.state.index];
if (word == value) {
alert('yes');
var nextIndex = (this.state.index == this.state.words.count-1)? 0 : this.state.index+1;
this.setState({ words:this.state.words, index:nextIndex });
}
}
render() {
return (
<div className="index">
<div>{this.renderWordsource()}</div>
<div>{this.renderWordinput()}</div>
</div>
);
}
}
// the input component
class WordinputComponent extends React.Component {
constructor(props) {
this.state = { text:''}
}
handleChange(event) {
var text = event.target.value;
this.props.onChange(this.props.id, text);
}
render() {
return (
<div className="wordinput-component">
<input type="text" onChange={this.handleChange.bind(this)} />
</div>
);
}
}
See where it says alert('yes')? That's where I think I should clear the value, but that doesn't make any sense because it's a parameter, not really the state of the component. Should I have the component pass itself to the change function? Maybe then I could alter it's state, but that sounds like a bad idea design-wise.
The 2 common ways of doing this is controlling the value through state in the parent or using a ref to clear the value. Added examples of both
The first one is using a ref and putting a function in the child component to clear
The second one is using state of the parent component and a controlled input field to clear it
class ParentComponent1 extends React.Component {
state = {
input2Value: ''
}
clearInput1() {
this.input1.clear();
}
clearInput2() {
this.setState({
input2Value: ''
});
}
handleInput2Change(evt) {
this.setState({
input2Value: evt.target.value
});
}
render() {
return (
<div>
<ChildComponent1 ref={input1 => this.input1 = input1}/>
<button onClick={this.clearInput1.bind(this)}>Clear</button>
<ChildComponent2 value={this.state.input2Value} onChange={this.handleInput2Change.bind(this)}/>
<button onClick={this.clearInput2.bind(this)}>Clear</button>
</div>
);
}
}
class ChildComponent1 extends React.Component {
clear() {
this.input.value = '';
}
render() {
return (
<input ref={input => this.input = input} />
);
}
}
class ChildComponent2 extends React.Component {
render() {
return (
<input value={this.props.value} onChange={this.props.onChange} />
);
}
}
ReactDOM.render(<ParentComponent1 />, document.body);
<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>
I had a similar issue: I wanted to clear a form which contained multiple fields.
While the two solutions by #noveyak are working fine, I want to share a different idea, which gives me the ability to partition the responsibility between parent and child: parent knows when to clear the form, and the items know how to react to that, without using refs.
The idea is to use a revision counter which gets incremented each time Clear is pressed and to react to changes of this counter in children.
In the example below there are three quite simple children reacting to the Clear button.
class ParentComponent extends React.Component {
state = {revision: 0}
clearInput = () => {
this.setState((prev) => ({revision: prev.revision+1}))
}
render() {
return (
<div>
<ChildComponent revision={this.state.revision}/>
<ChildComponent revision={this.state.revision}/>
<ChildComponent revision={this.state.revision}/>
<button onClick={this.clearInput.bind(this)}>Clear</button>
</div>
);
}
}
class ChildComponent extends React.Component {
state = {value: ''}
componentWillReceiveProps(nextProps){
if(this.props.revision != nextProps.revision){
this.setState({value : ''});
}
}
saveValue = (event) => {
this.setState({value: event.target.value})
}
render() {
return (
<input value={this.state.value} onChange={this.saveValue} />
);
}
}
ReactDOM.render(<ParentComponent />, document.body);
<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>
EDIT:
I've just stumbled upon this beautifully simple solution with key which is somewhat similar in spirit (you can pass parents's revision as child's key)
Very very very simple solution to clear form is add unique key in div under which you want to render form from your child component key={new Date().getTime()}:
render(){
return(
<div className="form_first_step fields_black" key={new Date().getTime()}>
<Form
className="first_step">
// form fields coming from child component
<AddressInfo />
</div>
</Form>
</div>
)
}
I'm trying to use the react-bootstrap checkbox (https://react-bootstrap.github.io/components.html#forms-controls) and I need to fire an event when it changes state. It would also be great to be able to programatically un/check it and/or tell if it is checked. Unfortunately when the code is transpiled and rendered it wraps the input in a div.
How can I find this in the dom and manipulate it?
My code looks similar to this:
import React, { PropTypes } from 'react';
import { Checkbox } from 'react-bootstrap';
const EditItem = (props) => {
return (
<div>
<Checkbox style={{ marginLeft: '15px' }} >{props.itemLable}</Checkbox>
</div>
);
};
export default EditItem;
And the browser renders this:
...
<div class="checkbox" style="margin-left: 15px;">
<label>
<input type="checkbox">
</label>
</div>
...
I see the inputRef prop in the documentation but I can't find any examples of this or get it to work myself.
There are two ways: The React way and the not-so-React way.
The React way is to set the child component's state by passing it props and respond to changes in its state by attaching event handlers. In the case of Checkbox, that means setting the checked and onChange props.
Note in the below example how the parent component (App) keeps track of the Checkbox's state and can both set it with this.setState and query it with this.state.checkboxChecked.
const { Checkbox, Button } = ReactBootstrap;
class App extends React.Component {
constructor() {
super();
this.state = { checkboxChecked: false };
this.handleChange = this.handleChange.bind(this);
this.handleIsItChecked = this.handleIsItChecked.bind(this);
this.handleToggle = this.handleToggle.bind(this);
}
render() {
return (
<div>
<Checkbox
checked={this.state.checkboxChecked}
onChange={this.handleChange} />
<Button type="button" onClick={this.handleToggle}>Toggle</Button>
<Button type="button" onClick={this.handleIsItChecked}>Is it checked?</Button>
</div>
);
}
handleChange(evt) {
this.setState({ checkboxChecked: evt.target.checked });
}
handleIsItChecked() {
console.log(this.state.checkboxChecked ? 'Yes' : 'No');
}
handleToggle() {
this.setState({ checkboxChecked: !this.state.checkboxChecked });
}
}
ReactDOM.render(<App/>, document.querySelector('div'));
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/latest/css/bootstrap.min.css">
<script src="//cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/react-bootstrap/0.30.8/react-bootstrap.min.js"></script>
<div></div>
The not-so-React way is to get a reference to the rendered DOM element and access its checked property directly. I don't recommend this, because it necessarily pollutes your lovely functional React code with icky imperative code. Nevertheless, with React-Bootstrap you can do it by setting the inputRef prop, as in the below example:
const { Checkbox, Button } = ReactBootstrap;
class App extends React.Component {
constructor() {
super();
this.handleIsItChecked = this.handleIsItChecked.bind(this);
this.handleToggle = this.handleToggle.bind(this);
}
render() {
return (
<div>
<Checkbox
onChange={this.handleChange}
inputRef={ref => this.myCheckbox = ref} />
<Button type="button" onClick={this.handleToggle}>Toggle</Button>
<Button type="button" onClick={this.handleIsItChecked}>Is it checked?</Button>
</div>
);
}
handleIsItChecked() {
console.log(this.myCheckbox.checked ? 'Yes' : 'No');
}
handleToggle() {
this.myCheckbox.checked = !this.myCheckbox.checked;
}
}
ReactDOM.render(<App/>, document.querySelector('div'));
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/latest/css/bootstrap.min.css">
<script src="//cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/react-bootstrap/0.30.8/react-bootstrap.min.js"></script>
<div></div>
Thanks for the above answers. I generalized the above slightly for use when you have more than one checkbox in a given component:
constructor() {
super();
this.state = { YourInputName: false };
this.handleCheckboxChange = this.handleCheckboxChange.bind(this);
}
render() {
return (
<div>
<Checkbox
name="YourInputName"
onChange={this.handleCheckboxChange} />
</div>
);
}
handleCheckboxChange(event) {
const target = event.target
const checked = target.checked
const name = target.name
this.setState({
[name]: checked,
});
}
Have you tried setting an onChange property to your checkbox?
handleChange(event) {
this.setState(*set checkbox state here*);
}
<Checkbox onChange={this.handleChange}></Checkbox>
I am messing around with React.js for the first time and cannot find a way to show or hide something on a page via click event. I am not loading any other library to the page, so I am looking for some native way using the React library. This is what I have so far. I would like to show the results div when the click event fires.
var Search= React.createClass({
handleClick: function (event) {
console.log(this.prop);
},
render: function () {
return (
<div className="date-range">
<input type="submit" value="Search" onClick={this.handleClick} />
</div>
);
}
});
var Results = React.createClass({
render: function () {
return (
<div id="results" className="search-results">
Some Results
</div>
);
}
});
React.renderComponent(<Search /> , document.body);
React circa 2020
In the onClick callback, call the state hook's setter function to update the state and re-render:
const Search = () => {
const [showResults, setShowResults] = React.useState(false)
const onClick = () => setShowResults(true)
return (
<div>
<input type="submit" value="Search" onClick={onClick} />
{ showResults ? <Results /> : null }
</div>
)
}
const Results = () => (
<div id="results" className="search-results">
Some Results
</div>
)
ReactDOM.render(<Search />, document.querySelector("#container"))
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.13.1/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.13.1/umd/react-dom.production.min.js"></script>
<div id="container">
<!-- This element's contents will be replaced with your component. -->
</div>
JSFiddle
React circa 2014
The key is to update the state of the component in the click handler using setState. When the state changes get applied, the render method gets called again with the new state:
var Search = React.createClass({
getInitialState: function() {
return { showResults: false };
},
onClick: function() {
this.setState({ showResults: true });
},
render: function() {
return (
<div>
<input type="submit" value="Search" onClick={this.onClick} />
{ this.state.showResults ? <Results /> : null }
</div>
);
}
});
var Results = React.createClass({
render: function() {
return (
<div id="results" className="search-results">
Some Results
</div>
);
}
});
ReactDOM.render( <Search /> , document.getElementById('container'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.6.2/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/15.6.2/react-dom.min.js"></script>
<div id="container">
<!-- This element's contents will be replaced with your component. -->
</div>
JSFiddle
<style type="text/css">
.hidden { display:none; }
</style>
const Example = props =>
<div className={props.shouldHide? 'hidden' : undefined}>Hello</div>
Here is an alternative syntax for the ternary operator:
{ this.state.showMyComponent ? <MyComponent /> : null }
is equivalent to:
{ this.state.showMyComponent && <MyComponent /> }
Learn why
Also alternative syntax with display: 'none';
<MyComponent style={this.state.showMyComponent ? {} : { display: 'none' }} />
However, if you overuse display: 'none', this leads to DOM pollution and ultimately slows down your application.
Here is my approach.
import React, { useState } from 'react';
function ToggleBox({ title, children }) {
const [isOpened, setIsOpened] = useState(false);
function toggle() {
setIsOpened(wasOpened => !wasOpened);
}
return (
<div className="box">
<div className="boxTitle" onClick={toggle}>
{title}
</div>
{isOpened && (
<div className="boxContent">
{children}
</div>
)}
</div>
);
}
In code above, to achieve this, I'm using code like:
{opened && <SomeElement />}
That will render SomeElement only if opened is true. It works because of the way how JavaScript resolve logical conditions:
true && true && 2; // will output 2
true && false && 2; // will output false
true && 'some string'; // will output 'some string'
opened && <SomeElement />; // will output SomeElement if `opened` is true, will output false otherwise (and false will be ignored by react during rendering)
// be careful with 'falsy' values eg
const someValue = [];
someValue.length && <SomeElement /> // will output 0, which will be rednered by react
// it'll be better to:
someValue.length > 0 && <SomeElement /> // will render nothing as we cast the value to boolean
Reasons for using this approach instead of CSS 'display: none';
While it might be 'cheaper' to hide an element with CSS - in such case 'hidden' element is still 'alive' in react world (which might make it actually way more expensive)
it means that if props of the parent element (eg. <TabView>) will change - even if you see only one tab, all 5 tabs will get re-rendered
the hidden element might still have some lifecycle methods running - eg. it might fetch some data from the server after every update even tho it's not visible
the hidden element might crash the app if it'll receive incorrect data. It might happen as you can 'forget' about invisible nodes when updating the state
you might by mistake set wrong 'display' style when making element visible - eg. some div is 'display: flex' by default, but you'll set 'display: block' by mistake with display: invisible ? 'block' : 'none' which might break the layout
using someBoolean && <SomeNode /> is very simple to understand and reason about, especially if your logic related to displaying something or not gets complex
in many cases, you want to 'reset' element state when it re-appears. eg. you might have a slider that you want to set to initial position every time it's shown. (if that's desired behavior to keep previous element state, even if it's hidden, which IMO is rare - I'd indeed consider using CSS if remembering this state in a different way would be complicated)
with the newest version react 0.11 you can also just return null to have no content rendered.
Rendering to null
This is a nice way to make use of the virtual DOM:
class Toggle extends React.Component {
state = {
show: true,
}
toggle = () => this.setState((currentState) => ({show: !currentState.show}));
render() {
return (
<div>
<button onClick={this.toggle}>
toggle: {this.state.show ? 'show' : 'hide'}
</button>
{this.state.show && <div>Hi there</div>}
</div>
);
}
}
Example here
Using React hooks:
const Toggle = () => {
const [show, toggleShow] = React.useState(true);
return (
<div>
<button
onClick={() => toggleShow(!show)}
>
toggle: {show ? 'show' : 'hide'}
</button>
{show && <div>Hi there</div>}
</div>
)
}
Example here
I created a small component that handles this for you: react-toggle-display
It sets the style attribute to display: none !important based on the hide or show props.
Example usage:
var ToggleDisplay = require('react-toggle-display');
var Search = React.createClass({
getInitialState: function() {
return { showResults: false };
},
onClick: function() {
this.setState({ showResults: true });
},
render: function() {
return (
<div>
<input type="submit" value="Search" onClick={this.onClick} />
<ToggleDisplay show={this.state.showResults}>
<Results />
</ToggleDisplay>
</div>
);
}
});
var Results = React.createClass({
render: function() {
return (
<div id="results" className="search-results">
Some Results
</div>
);
}
});
React.renderComponent(<Search />, document.body);
There are several great answers already, but I don't think they've been explained very well and several of the methods given contain some gotchas that might trip people up. So I'm going to go over the three main ways (plus one off-topic option) to do this and explain the pros and cons. I'm mostly writing this because Option 1 was recommended a lot and there's a lot of potential issues with that option if not used correctly.
Option 1: Conditional Rendering in the parent.
I don't like this method unless you're only going to render the component one time and leave it there. The issue is it will cause react to create the component from scratch every time you toggle the visibility.
Here's the example. LogoutButton or LoginButton are being conditionally rendered in the parent LoginControl. If you run this you'll notice the constructor is getting called on each button click. https://codepen.io/Kelnor/pen/LzPdpN?editors=1111
class LoginControl extends React.Component {
constructor(props) {
super(props);
this.handleLoginClick = this.handleLoginClick.bind(this);
this.handleLogoutClick = this.handleLogoutClick.bind(this);
this.state = {isLoggedIn: false};
}
handleLoginClick() {
this.setState({isLoggedIn: true});
}
handleLogoutClick() {
this.setState({isLoggedIn: false});
}
render() {
const isLoggedIn = this.state.isLoggedIn;
let button = null;
if (isLoggedIn) {
button = <LogoutButton onClick={this.handleLogoutClick} />;
} else {
button = <LoginButton onClick={this.handleLoginClick} />;
}
return (
<div>
<Greeting isLoggedIn={isLoggedIn} />
{button}
</div>
);
}
}
class LogoutButton extends React.Component{
constructor(props, context){
super(props, context)
console.log('created logout button');
}
render(){
return (
<button onClick={this.props.onClick}>
Logout
</button>
);
}
}
class LoginButton extends React.Component{
constructor(props, context){
super(props, context)
console.log('created login button');
}
render(){
return (
<button onClick={this.props.onClick}>
Login
</button>
);
}
}
function UserGreeting(props) {
return <h1>Welcome back!</h1>;
}
function GuestGreeting(props) {
return <h1>Please sign up.</h1>;
}
function Greeting(props) {
const isLoggedIn = props.isLoggedIn;
if (isLoggedIn) {
return <UserGreeting />;
}
return <GuestGreeting />;
}
ReactDOM.render(
<LoginControl />,
document.getElementById('root')
);
Now React is pretty quick at creating components from scratch. However, it still has to call your code when creating it. So if your constructor, componentDidMount, render, etc code is expensive, then it'll significantly slow down showing the component. It also means you cannot use this with stateful components where you want the state to be preserved when hidden (and restored when displayed.) The one advantage is that the hidden component isn't created at all until it's selected. So hidden components won't delay your initial page load. There may also be cases where you WANT a stateful component to reset when toggled. In which case this is your best option.
Option 2: Conditional Rendering in the child
This creates both components once. Then short circuits the rest of the render code if the component is hidden. You can also short circuit other logic in other methods using the visible prop. Notice the console.log in the codepen page. https://codepen.io/Kelnor/pen/YrKaWZ?editors=0011
class LoginControl extends React.Component {
constructor(props) {
super(props);
this.handleLoginClick = this.handleLoginClick.bind(this);
this.handleLogoutClick = this.handleLogoutClick.bind(this);
this.state = {isLoggedIn: false};
}
handleLoginClick() {
this.setState({isLoggedIn: true});
}
handleLogoutClick() {
this.setState({isLoggedIn: false});
}
render() {
const isLoggedIn = this.state.isLoggedIn;
return (
<div>
<Greeting isLoggedIn={isLoggedIn} />
<LoginButton isLoggedIn={isLoggedIn} onClick={this.handleLoginClick}/>
<LogoutButton isLoggedIn={isLoggedIn} onClick={this.handleLogoutClick}/>
</div>
);
}
}
class LogoutButton extends React.Component{
constructor(props, context){
super(props, context)
console.log('created logout button');
}
render(){
if(!this.props.isLoggedIn){
return null;
}
return (
<button onClick={this.props.onClick}>
Logout
</button>
);
}
}
class LoginButton extends React.Component{
constructor(props, context){
super(props, context)
console.log('created login button');
}
render(){
if(this.props.isLoggedIn){
return null;
}
return (
<button onClick={this.props.onClick}>
Login
</button>
);
}
}
function UserGreeting(props) {
return <h1>Welcome back!</h1>;
}
function GuestGreeting(props) {
return <h1>Please sign up.</h1>;
}
function Greeting(props) {
const isLoggedIn = props.isLoggedIn;
if (isLoggedIn) {
return <UserGreeting />;
}
return <GuestGreeting />;
}
ReactDOM.render(
<LoginControl />,
document.getElementById('root')
);
Now, if the initialization logic is quick and the children are stateless, then you won't see a difference in performance or functionality. However, why make React create a brand new component every toggle anyway? If the initialization is expensive however, Option 1 will run it every time you toggle a component which will slow the page down when switching. Option 2 will run all of the component's inits on first page load. Slowing down that first load. Should note again. If you're just showing the component one time based on a condition and not toggling it, or you want it to reset when toggledm, then Option 1 is fine and probably the best option.
If slow page load is a problem however, it means you've got expensive code in a lifecycle method and that's generally not a good idea. You can, and probably should, solve the slow page load by moving the expensive code out of the lifecycle methods. Move it to an async function that's kicked off by ComponentDidMount and have the callback put it in a state variable with setState(). If the state variable is null and the component is visible then have the render function return a placeholder. Otherwise render the data. That way the page will load quickly and populate the tabs as they load. You can also move the logic into the parent and push the results to the children as props. That way you can prioritize which tabs get loaded first. Or cache the results and only run the logic the first time a component is shown.
Option 3: Class Hiding
Class hiding is probably the easiest to implement. As mentioned you just create a CSS class with display: none and assign the class based on prop. The downside is the entire code of every hidden component is called and all hidden components are attached to the DOM. (Option 1 doesn't create the hidden components at all. And Option 2 short circuits unnecessary code when the component is hidden and removes the component from the DOM completely.) It appears this is faster at toggling visibility according some tests done by commenters on other answers but I can't speak to that.
Option 4: One component but change Props. Or maybe no component at all and cache HTML.
This one won't work for every application and it's off topic because it's not about hiding components, but it might be a better solution for some use cases than hiding. Let's say you have tabs. It might be possible to write one React Component and just use the props to change what's displayed in the tab. You could also save the JSX to state variables and use a prop to decide which JSX to return in the render function. If the JSX has to be generated then do it and cache it in the parent and send the correct one as a prop. Or generate in the child and cache it in the child's state and use props to select the active one.
You set a boolean value in the state (e.g. 'show)', and then do:
var style = {};
if (!this.state.show) {
style.display = 'none'
}
return <div style={style}>...</div>
A simple method to show/hide elements in React using Hooks
const [showText, setShowText] = useState(false);
Now, let's add some logic to our render method:
{showText && <div>This text will show!</div>}
And
onClick={() => setShowText(!showText)}
Good job.
I was able to use css property "hidden". Don't know about possible drawbacks.
export default function App() {
const [hidden, setHidden] = useState(false);
return (
<div>
<button onClick={() => setHidden(!hidden)}>HIDE</button>
<div hidden={hidden}>hidden component</div>
</div>
);
}
Best practice is below according to the documentation:
{this.state.showFooter && <Footer />}
Render the element only when the state is valid.
Simple hide/show example with React Hooks: (srry about no fiddle)
const Example = () => {
const [show, setShow] = useState(false);
return (
<div>
<p>Show state: {show}</p>
{show ? (
<p>You can see me!</p>
) : null}
<button onClick={() => setShow(!show)}>
</div>
);
};
export default Example;
class FormPage extends React.Component{
constructor(props){
super(props);
this.state = {
hidediv: false
}
}
handleClick = (){
this.setState({
hidediv: true
});
}
render(){
return(
<div>
<div className="date-range" hidden = {this.state.hidediv}>
<input type="submit" value="Search" onClick={this.handleClick} />
</div>
<div id="results" className="search-results" hidden = {!this.state.hidediv}>
Some Results
</div>
</div>
);
}
}
I start with this statement from the React team:
In React, you can create distinct components that encapsulate behaviour
you need. Then, you can render only some of them, depending on the
state of your application.
Conditional rendering in React works the same way conditions work in
JavaScript. Use JavaScript operators like if or the conditional
operator to create elements representing the current state, and let
React update the UI to match them.
You basically need to show the component when the button gets clicked, you can do it two ways, using pure React or using CSS, using pure React way, you can do something like below code in your case, so in the first run, results are not showing as hideResults is true, but by clicking on the button, state gonna change and hideResults is false and the component get rendered again with the new value conditions, this is very common use of changing component view in React...
var Search = React.createClass({
getInitialState: function() {
return { hideResults: true };
},
handleClick: function() {
this.setState({ hideResults: false });
},
render: function() {
return (
<div>
<input type="submit" value="Search" onClick={this.handleClick} />
{ !this.state.hideResults && <Results /> }
</div> );
}
});
var Results = React.createClass({
render: function() {
return (
<div id="results" className="search-results">
Some Results
</div>);
}
});
ReactDOM.render(<Search />, document.body);
If you want to do further study in conditional rendering in React, have a look here.
class Toggle extends React.Component {
state = {
show: true,
}
render() {
const {show} = this.state;
return (
<div>
<button onClick={()=> this.setState({show: !show })}>
toggle: {show ? 'show' : 'hide'}
</button>
{show && <div>Hi there</div>}
</div>
);
}
}
If you would like to see how to TOGGLE the display of a component checkout this fiddle.
http://jsfiddle.net/mnoster/kb3gN/16387/
var Search = React.createClass({
getInitialState: function() {
return {
shouldHide:false
};
},
onClick: function() {
console.log("onclick");
if(!this.state.shouldHide){
this.setState({
shouldHide: true
})
}else{
this.setState({
shouldHide: false
})
}
},
render: function() {
return (
<div>
<button onClick={this.onClick}>click me</button>
<p className={this.state.shouldHide ? 'hidden' : ''} >yoyoyoyoyo</p>
</div>
);
}
});
ReactDOM.render( <Search /> , document.getElementById('container'));
Use ref and manipulate CSS
One way could be to use React's ref and manipulate CSS class using the browser's API. Its benefit is to avoid rerendering in React if the sole purpose is to hide/show some DOM element on the click of a button.
// Parent.jsx
import React, { Component } from 'react'
export default class Parent extends Component {
constructor () {
this.childContainer = React.createRef()
}
toggleChild = () => {
this.childContainer.current.classList.toggle('hidden')
}
render () {
return (
...
<button onClick={this.toggleChild}>Toggle Child</button>
<div ref={this.childContainer}>
<SomeChildComponent/>
</div>
...
);
}
}
// styles.css
.hidden {
display: none;
}
PS Correct me if I am wrong. :)
In some cases higher order component might be useful:
Create higher order component:
export var HidableComponent = (ComposedComponent) => class extends React.Component {
render() {
if ((this.props.shouldHide!=null && this.props.shouldHide()) || this.props.hidden)
return null;
return <ComposedComponent {...this.props} />;
}
};
Extend your own component:
export const MyComp= HidableComponent(MyCompBasic);
Then you can use it like this:
<MyComp hidden={true} ... />
<MyComp shouldHide={this.props.useSomeFunctionHere} ... />
This reduces a bit boilerplate and enforces sticking to naming conventions, however please be aware of that MyComp will still be instantiated - the way to omit is was mentioned earlier:
{ !hidden && <MyComp ... /> }
If you use bootstrap 4, you can hide element that way
className={this.state.hideElement ? "invisible" : "visible"}
Use rc-if-else module
npm install --save rc-if-else
import React from 'react';
import { If } from 'rc-if-else';
class App extends React.Component {
render() {
return (
<If condition={this.props.showResult}>
Some Results
</If>
);
}
}
Use this lean and short syntax:
{ this.state.show && <MyCustomComponent /> }
Here comes the simple, effective and best solution with a Classless React Component for show/hide the elements. Use of React-Hooks which is available in the latest create-react-app project that uses React 16
import React, {useState} from 'react';
function RenderPara(){
const [showDetail,setShowDetail] = useState(false);
const handleToggle = () => setShowDetail(!showDetail);
return (
<React.Fragment>
<h3>
Hiding some stuffs
</h3>
<button onClick={handleToggle}>Toggle View</button>
{showDetail && <p>
There are lot of other stuffs too
</p>}
</React.Fragment>)
}
export default RenderPara;
Happy Coding :)
//use ternary condition
{ this.state.yourState ? <MyComponent /> : null }
{ this.state.yourState && <MyComponent /> }
{ this.state.yourState == 'string' ? <MyComponent /> : ''}
{ this.state.yourState == 'string' && <MyComponent /> }
//Normal condition
if(this.state.yourState){
return <MyComponent />
}else{
return null;
}
<button onClick={()=>this.setState({yourState: !this.props.yourState}>Toggle View</button>
Just figure out a new and magic way with using(useReducer) for functional components
const [state, handleChangeState] = useReducer((state) => !state, false);
change state
This can also be achieved like this (very easy way)
class app extends Component {
state = {
show: false
};
toggle= () => {
var res = this.state.show;
this.setState({ show: !res });
};
render() {
return(
<button onClick={ this.toggle }> Toggle </button>
{
this.state.show ? (<div> HELLO </div>) : null
}
);
}
this example shows how you can switch between components by using a toggle which switches after every 1sec
import React ,{Fragment,Component} from "react";
import ReactDOM from "react-dom";
import "./styles.css";
const Component1 = () =>(
<div>
<img
src="https://i.pinimg.com/originals/58/df/1d/58df1d8bf372ade04781b8d4b2549ee6.jpg" />
</div>
)
const Component2 = () => {
return (
<div>
<img
src="http://www.chinabuddhismencyclopedia.com/en/images/thumb/2/2e/12ccse.jpg/250px-
12ccse.jpg" />
</div>
)
}
class App extends Component {
constructor(props) {
super(props);
this.state = {
toggleFlag:false
}
}
timer=()=> {
this.setState({toggleFlag:!this.state.toggleFlag})
}
componentDidMount() {
setInterval(this.timer, 1000);
}
render(){
let { toggleFlag} = this.state
return (
<Fragment>
{toggleFlag ? <Component1 /> : <Component2 />}
</Fragment>
)
}
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);
The application of states and effects has and must be encapsulated in the same component, for this reason, there is nothing better than creating a custom component as a hook to solve in this case whether to make particular blocks or elements visible or invisible.
// hooks/useOnScreen.js
import { useState, useEffect } from "react"
const useOnScreen = (ref, rootMargin = "0px") => {
const [isVisible, setIsVisible] = useState(false)
useEffect(() => {
const observer = new IntersectionObserver(
([entry]) => {
setIsVisible(entry.isIntersecting)
},
{
rootMargin
}
);
const currentElement = ref?.current
if (currentElement) {
observer.observe(currentElement)
}
return () => {
observer.unobserve(currentElement)
}
}, [])
return isVisible
}
export default useOnScreen
Then the custom hook is embedded inside the component
import React, { useRef } from "react";
import useOnScreen from "hooks/useOnScreen";
const MyPage = () => {
const ref = useRef(null)
const isVisible = useOnScreen(ref)
const onClick = () => {
console.log("isVisible", isVisible)
}
return (
<div ref={ref}>
<p isVisible={isVisible}>
Something is visible
</p>
<a
href="#"
onClick={(e) => {
e.preventDefault();
onClick(onClick)
}}
>
Review
</a>
</div>
)
}
export default MyPage
The ref variable, controlled by the useRef hook, allows us to capture the location in the DOM of the block that we want to control, then the isVisible variable, controlled by the useOnScreen hook, allows us to make the inside the block I signal by the useRef hook.
I believe that this implementation of the useState, useEfect, and useRef hooks allows you to avoid component rendering by separating them using custom hooks.
Hoping that this knowledge will be of use to you.
It is very simple to hide and show the elements in react.
There are multiple ways but I will show you two.
Way 1:
const [isVisible, setVisible] = useState(false)
let onHideShowClick = () =>{
setVisible(!isVisible)
}
return (<div>
<Button onClick={onHideShowClick} >Hide/Show</Button>
{(isVisible) ? <p>Hello World</p> : ""}
</div>)
Way 2:
const [isVisible, setVisible] = useState(false)
let onHideShowClick = () =>{
setVisible(!isVisible)
}
return (<div>
<Button onClick={onHideShowClick} >Hide/Show</Button>
<p style={{display: (isVisible) ? 'block' : 'none'}}>Hello World</p>
</div>)
It is just working like if and else.
In Way one, it will remove and re-render elements in Dom.
In the Second way you are just displaying elements as false or true.
Thank you.
You've to do the small change in the code for continuously hiding and showing
const onClick = () => {setShowResults(!showResults}
Problem will be solved
const Search = () => {
const [showResults, setShowResults] = React.useState(false)
const onClick = () => setShowResults(true)
const onClick = () => {setShowResults(!showResults}
return (
<div>
<input type="submit" value="Search" onClick={onClick} />
{ showResults ? <Results /> : null }
</div>
)
}
const Results = () => (
<div id="results" className="search-results">
Some Results
</div>
)
ReactDOM.render(<Search />, document.querySelector("#container"))
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.13.1/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.13.1/umd/react-dom.production.min.js"></script>
<div id="container">
<!-- This element's contents will be replaced with your component. -->
</div>
```