Is there any way to add dynamical li element into my ul list ?
I'd like add my li by clicking the button. Here is example code
class Component1 extends React.Component {
constructor() {
super();
}
add() {
let ul = document.getElementById('mylist');
let li = document.createElement('li');
li.appendChild(document.createTextNode({some_variables});
ul.appendChild(li);
}
render() {
return (
<a href="#" onClick={() => this.add()}>Add</a>
<ul id="mylist">
/* dynamic list ITEM */
</ul>
);
}
}
ReactDOM.render(<Component1 />, document.getElementById('root'));
Of course current function add() doesn't work on React
When using react we are not "touching" the DOM as we usually do with other libraries (like jQuery).
One of the best and core features of react is the virtual DOM, the Reconciliation & diffing algorithm
React builds and maintains an internal representation of the rendered
UI. It includes the React elements you return from your components.
This representation lets React avoid creating DOM nodes and accessing
existing ones beyond necessity, as that can be slower than operations
on JavaScript objects. Sometimes it is referred to as a “virtual DOM”
In react you create components (functions) that renders / returns a jsx (markup).
A simple example to your scenario could be:
const ListItem = ({ value, onClick }) => (
<li onClick={onClick}>{value}</li>
);
const List = ({ items, onItemClick }) => (
<ul>
{
items.map((item, i) => <ListItem key={i} value={item} onClick={onItemClick} />)
}
</ul>
);
class App extends React.Component {
constructor(props) {
super(props);
this.state = {
inputValue: '',
fruites: ['Apple', 'Banana', 'Orange']
};
}
onClick = () => {
const { inputValue, fruites } = this.state;
if (inputValue) {
const nextState = [...fruites, inputValue];
this.setState({ fruites: nextState, inputValue: '' });
}
}
onChange = (e) => this.setState({ inputValue: e.target.value });
handleItemClick = (e) => {console.log(e.target.innerHTML)}
render() {
const { fruites, inputValue } = this.state;
return (
<div>
<input type="text" value={inputValue} onChange={this.onChange} />
<button onClick={this.onClick}>Add</button>
<List items={fruites} onItemClick={this.handleItemClick} />
</div>
);
}
}
ReactDOM.render(<App />, document.getElementById("root"));
<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="root"></div>
Related
I'm running into the issue where I have created a functional component to render a dropdown menu, however I cannot update the initial state in the main App.JS. I'm not really sure how to update the state unless it is in the same component.
Here is a snippet of my App.js where I initialize the items array and call the functional component.
const items = [
{
id: 1,
value:'item1'
},
{
id: 2,
value:'item2'
},
{
id: 3,
value:'item3'
}
]
class App extends Component{
state = {
item: ''
}
...
render(){
return{
<ItemList title = "Select Item items= {items} />
And here is my functional componenet. Essentially a dropdown menu from a YouTube tutorial I watched (https://www.youtube.com/watch?v=t8JK5bVoVBw).
function ItemList ({title, items, multiSelect}) {
const [open, setOpen] = useState (false);
const [selection, setSelection] = useState([]);
const toggle =() =>setOpen(!open);
ItemList.handleClickOutside = ()=> setOpen(false);
function handleOnClick(item) {
if (!selection.some(current => current.id == item.id)){
if (!multiSelect){
setSelection([item])
}
else if (multiSelect) {
setSelection([...selection, item])
}
}
else{
let selectionAfterRemoval = selection;
selectionAfterRemoval = selectionAfterRemoval.filter(
current =>current.id == item.id
)
setSelection([...selectionAfterRemoval])
}
}
function itemSelected(item){
if (selection.find(current =>current.id == item.id)){
return true;
}
return false;
}
return (
<div className="dd-wraper">
<div tabIndex={0}
className="dd-header"
role="button"
onKeyPress={() => toggle(!open)}
onClick={() =>toggle(!open)}
onChange={(e) => this.setState({robot: e.target.value})}
>
<div className="dd-header_title">
<p className = "dd-header_title--bold">{title}</p>
</div>
<div className="dd-header_action">
<p>{open ? 'Close' : 'Open'}</p>
</div>
</div>
{open && (
<ul className ="dd-list">
{item.map(item =>(
<li className="dd-list-item" key={item.id}>
<button type ="button"
onClick={() => handleOnClick(item)}>
<span>{item.value}</span>
<span>{itemSelected(item) && 'Selected'}</span>
</button>
</li>
))}
</ul>
)}
</div>
)
}
const clickOutsideConfig ={
handleClickOutside: () => RobotList.handleClickOutside
}
I tried passing props and mutating the state in the functional component, but nothing gets changed. I suspect that it needs to be changed in the itemSelected function, but I'm not sure how. Any help would be greatly appreciated!
In a function component, you have the setters of the state variables. In your example, you can directly use setOpen(...) or setSelection(...). In case of a boolean state variable, you could just toggle by using setOpen(!open). See https://reactjs.org/docs/hooks-state.html (Chapter "Updating State") for further details.
So you need to do something like below . Here we are passing handleChange in parent Component as props to the child component and in Child Component we are calling the method as props.onChange
Parent Component:
class Parent extends React.Component {
constructor(props) {
super(props)
this.state = {
value :''
}
}
handleChange = (newValue) => {
this.setState({ value: newValue });
}
render() {
return <Child value={this.state.value} onChange = {this.handleChange} />
}
}
Child Component:
function Child(props) {
function handleChange(event) {
// Here, we invoke the callback with the new value
props.onChange(event.target.value);
}
return <input value={props.value} onChange={handleChange} />
}
I'm very new to JS and React and coding in general. I'm trying to remove an item from an array using onClick, like so:
const { Component } = React;
class Board extends Component{
constructor(props) {
super(props);
this.state = {
comments: [
'I like Rosie',
'I like you',
'I like bacon',
'lalalala'
],
}
}
removeComment = (e) =>{
var filteredArray = this.state.comments.filter(item => item !== e.target.value)
this.setState({comments: filteredArray});
console.log(e.target.value)
}
eachComment = (text, i) => {
return ( <p id={i} key={i} > comment: {text} {i}</p> )
}
render(){
console.log('render');
return (
<div className="gif-list" onClick={this.removeComment}>
{this.state.comments.map(this.eachComment)}
</div>
);
}
}
ReactDOM.render(
<Board/>,
document.querySelector('#mount'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<div id="mount"><div>
Not much is happening though. My console.log(e.target.value) comes back as undefined. What am I doing wrong?
I have tried looking at other answers but implementing (to me) abstract solutions to other similar problems is not working for me.
Thanks in advance, and apologies for such a simple question.
The div you have the event handler on does not have a value attribute. But even if it did I don't think it will do what you want.
You'll need to change your code a bit in order to get it working like you want:
class Board extends React.Component{
constructor(props) {
super(props);
this.state = {
comments: [
'I like Rosie',
'I like you',
'I like bacon',
'lalalala'
],
}
}
removeComment = (e) =>{
// Check the index in the filter to see if it should be kept or removed
var filteredArray = this.state.comments.filter((item, i) => i != e.target.id)
this.setState({comments: filteredArray});
console.log(e.target.id)
}
eachComment = (text, i) => {
// Move the event handler to be on each item
return ( <p id={i} key={i} onClick={this.removeComment}> comment: {text} {i}</p> )
}
render(){
return (
<div className="gif-list">
{this.state.comments.map(this.eachComment)}
</div>
);
}
}
ReactDOM.render(<Board />, document.getElementById('root'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<div id="root" />
You'll notice the important changes are:
Give the remove handler to each mapped element
Use an attribute from the event target that actually exists and can be used to determine which element should be removed.
For this one you need to specifically pass in the param when you bind the onClick function
return (
<div className="gif-list" onClick={(e)=>this.removeComment(e)}>
{this.state.comments.map(this.eachComment)}
</div>
);
I am trying to create something similar to React Bootstrap's dropdown component. My starting skeleton is something like the following:
import React from 'react';
const DropDown = props => {
return <div className="dropdown-container">{props.children}</div>;
};
const DropDownToggle = props => {
return <div className="dropdown-toggle">{props.children}</div>;
};
const DropDownContent = props => {
return <div className="dropdown-content">{props.children}</div>;
};
export { DropDown, DropDownToggle, DropDownContent };
These components would be used like this:
<DropDown>
<DropDownToggle>
{/*
The content inside here should be customizable so the user of
these components can specify whatever they want for the toggle
*/}
<button type="button">
my button
</button>
</DropDownToggle>
<DropDownContent>
{/*
The content inside here should be customizable so the user of
these components can specify whatever they want for the content of
the dropdown
*/}
<ContentComponent/>
</DropDownContent>
</DropDown>
Is there a way I can communicate between the two children components (DropDownContent and DropDownToggle)? I have access to the parent component and it just receives and displays the children so far, but I would like to somehow communicate between the children so that the user can click on the toggle to open/close the content. I don't want to use redux.
Thank you in advance!
EDIT
I ended up going with the method that #Train suggested in his/her comment below. I was originally hoping for the ability to nest components manually, but what was most important to me was having the state be self-contained in the parent component. Being able to define the toggle button's HTML as well as the content's HTML was also a requirement. My final implementation allows for both of these things and looks something like this:
import React from 'react';
import PropTypes from 'prop-types';
export class Dropdown extends React.Component {
state = {
isOpen: false,
};
onDropDownToggleClick = () => {
this.setState({ isOpen: !this.state.isOpen });
};
render() {
let contentClasses = 'dropdown-content';
if (this.state.isOpen) {
contentClasses += ' show';
}
return (
<div className="dropdown-container">
<div className="dropdown-toggle" onClick={this.onDropDownToggleClick}>
{this.props.toggle}
</div>
<div className={contentClasses}>{this.props.content}</div>
</div>
);
}
}
Dropdown.propTypes = {
toggle: PropTypes.oneOfType([PropTypes.string, PropTypes.element]).isRequired,
content: PropTypes.oneOfType([PropTypes.string, PropTypes.element])
.isRequired,
};
export default Dropdown;
to use it:
const dropDownToggle = (
<button type="button">
Dropdown
</button>
);
const dropDownContent = 'content';
<DropDown
toggle={dropDownToggle}
content={dropDownContent}
/>
For something like toggling content you can use composition instead of inheritance to pass data around.
From the example of Facebook
This is done with props.children property.
function Dialog(props) {
return (
<FancyBorder color="blue">
<h1 className="Dialog-title">
{props.title}
</h1>
<p className="Dialog-message">
{props.message}
</p>
{props.children}
</FancyBorder>
);
}
class SignUpDialog extends React.Component {
constructor(props) {
super(props);
this.handleChange = this.handleChange.bind(this);
this.handleSignUp = this.handleSignUp.bind(this);
this.state = {login: ''};
}
render() {
return (
<Dialog title="Mars Exploration Program"
message="How should we refer to you?">
<input value={this.state.login}
onChange={this.handleChange} />
<button onClick={this.handleSignUp}>
Sign Me Up!
</button>
</Dialog>
);
}
handleChange(e) {
this.setState({login: e.target.value});
}
handleSignUp() {
alert(`Welcome aboard, ${this.state.login}!`);
}
}
In the render() I am rendering the Dialog component and passing in the props.
the props are .children and the custom props title, message
This lets us pass child elements directly into the output we can even add components from other classes as I did with the SignUpDialog.
Did you have something like this in mind?
const actionTypes = {
TOGGLE: "TOGGLE"
};
const notRedux = {
actionHandlers: Object.keys(actionTypes).reduce(
(acc, val) => ({ [val]: [], ...acc }),
{}
),
dispatchAction(actionType, data) {
this.actionHandlers[actionType].forEach(handler => handler(data));
},
onAction(actionType, actionHandler) {
this.actionHandlers[actionType].push(actionHandler);
}
};
const DropDown = ({ children }) => {
return <div className="dropdown-container">{children}</div>;
};
const DropDownToggle = () => {
const onClick = () =>
notRedux.dispatchAction(actionTypes.TOGGLE, "oh hi Mark");
return (
<div className="dropdown-toggle">
<button type="button" onClick={onClick}>
my button
</button>
</div>
);
};
const DropDownContent = props => {
notRedux.onAction(actionTypes.TOGGLE, data =>
alert(`DropDownToggle said ${data} //DropDownContent`)
);
return <div className="dropdown-content">{props.children}</div>;
};
const App = () => (
<DropDown>
<DropDownToggle></DropDownToggle>
<DropDownContent>
<span>Content goes here</span>
</DropDownContent>
</DropDown>
);
ReactDOM.render(<App />, document.getElementById("app"));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<div id="app"></app>
I'm new to ReactJS and I would like to communicate between my components.
When I click an image in my "ChildA" I want to update the correct item image in my "ChildB" (type attribute in ChildA can only be "itemone", "itemtwo", "itemthree"
Here is what it looks like
Parent.js
export default class Parent extends Component {
render() {
return (
<div className="mainapp" id="app">
<ChildA/>
<ChildB/>
</div>
);
}
}
if (document.getElementById('page')) {
ReactDOM.render(<Builder />, document.getElementById('page'));
}
ChildA.js
render() {
return _.map(this.state.eq, ecu => {
return (
<img src="../images/misc/ec.png" type={ecu.type_eq} onClick={() => this.changeImage(ecu.img)}/>
);
});
}
ChildB.js
export default class CharacterForm extends Component {
constructor(props) {
super(props);
this.state = {
items: [
{ name: "itemone" image: "defaultone.png"},
{ name: "itemtwo" image: "defaulttwo.png"},
{ name: "itemthree" image: "defaultthree.png"},
]
};
}
render() {
return (
<div className="items-column">
{this.state.items.map(item => (<FrameCharacter key={item.name} item={item} />))}
</div>
);
}
}
I can retrieve the image on my onClick handler in my ChildA but I don't know how to give it to my ChildB. Any hints are welcomed, thanks you!
What you need is for Parent to pass an event handler down to ChildA which ChildA will call when one of the images is clicked. The event handler will call setState in Parent to update its state with the given value, and then Parent will pass the value down to ChildB in its render method.
You can see this working in the below example. Since I don't have any actual images to work with—and to keep it simple—I've used <button>s instead, but the principle is the same.
class Parent extends React.Component {
constructor(props) {
super(props);
this.state = {
clickedItem: 'none',
};
}
render() {
return (
<div>
<ChildA onClick={this.handleChildClick}/>
<ChildB clickedItem={this.state.clickedItem}/>
</div>
);
}
handleChildClick = clickedItem => {
this.setState({ clickedItem });
}
}
const items = ['item1', 'item2', 'item3'];
const ChildA = ({ onClick }) => (
<div>
{items.map(name => (
<button key={name} type="button" onClick={() => onClick(name)}>
{name}
</button>
))}
</div>
);
const ChildB = ({clickedItem}) => (
<p>Clicked item: {clickedItem}</p>
);
ReactDOM.render(<Parent/>, document.querySelector('div'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.development.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.development.js"></script>
<div></div>
Iam new to React and I'm trying to interact with the swapi API.
I want to get the list of films (movie titles list) and when I click on a title to show the opening_crawl from the json object.
I managed to get the film titles in an array. I don't know how to proceed from here.
Here is my code:
class StarWarsApp extends React.Component {
render() {
const title = "Star Wars";
const subtitle = "Movies";
return (
<div>
<Header title={title} />
<Movies />
</div>
);
}
}
class Header extends React.Component {
render() {
return (
<div>
<h1>{this.props.title}</h1>
</div>
);
}
}
class Movies extends React.Component {
constructor(props) {
super(props);
this.handleMovies = this.handleMovies.bind(this);
this.state = {
movies: []
};
this.handleMovies();
}
handleMovies() {
fetch("https://swapi.co/api/films")
.then(results => {
return results.json();
})
.then(data => {
console.log(data);
let movies = data.results.map(movie => {
return <div key={movie.episode_id}>{movie.title}</div>;
});
this.setState(() => {
return {
movies: movies
};
});
});
}
render() {
return (
<div>
<h1>Episodes</h1>
<div>{this.state.movies}</div>
</div>
);
}
}
ReactDOM.render(<StarWarsApp />, document.getElementById("app"));
To iterate over movies add this in render method:
render(){
return (
<div>
<h1>Episodes</h1>
{
this.state.movies.map((movie, i) => {
return (
<div className="movie" onClick={this.handleClick} key={i}>{movie.title}
<div className="opening">{movie.opening_crawl}</div>
</div>
);
})
}
</div>
);
}
Add this method to your Movies component to add active class on click to DIV with "movie" className:
handleClick = event => {
event.currentTarget.classList.toggle('active');
}
Include this css to your project:
.movie .opening {
display: none;
}
.active .opening {
display: block
}
After fetching the data, just keep it in your state then use the pieces in your components or JSX. Don't return some JSX from your handleMovies method, just do the setState part there. Also, I suggest using a life-cycle method (or hooks API maybe if you use a functional component) to trigger the fetching. By the way, don't use class components unless you need a state or life-cycle methods.
After that, you can render your titles in your render method by mapping the movies state. Also, you can have a place for your opening_crawls part and render it with a conditional operator. This condition changes with a click. To do that you have an extra state property and keep the movie ids there. With the click, you can set the id value to true and show the crawls.
Here is a simple working example.
const StarWarsApp = () => {
const title = "Star Wars";
const subtitle = "Movies";
return (
<div>
<Header title={title} />
<Movies />
</div>
);
}
const Header = ({ title }) => (
<div>
<h1>{title}</h1>
</div>
);
class Movies extends React.Component {
state = {
movies: [],
showCrawl: {}
};
componentDidMount() {
this.handleMovies();
}
handleMovies = () =>
fetch("https://swapi.co/api/films")
.then(results => results.json())
.then(data => this.setState({ movies: data.results }));
handleCrawl = e => {
const { id } = e.target;
this.setState(current => ({
showCrawl: { ...current.showCrawl, [id]: !current.showCrawl[id] }
}));
};
render() {
return (
<div>
<h1>Episodes</h1>
<div>
{this.state.movies.map(movie => (
<div
key={movie.episode_id}
id={movie.episode_id}
onClick={this.handleCrawl}
>
{movie.title}
{this.state.showCrawl[movie.episode_id] && (
<div style={{ border: "1px black solid" }}>
{movie.opening_crawl}
</div>
)}
</div>
))}
</div>
</div>
);
}
}
ReactDOM.render(<StarWarsApp />, document.getElementById("root"));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<div id="root"></div>
I am using id on the target div to get it back from the event object. I don't like this method too much but for the sake of clarity, I used this. You can refactor it and create another component may be, then you can pass the epoisde_id there and handle the setState part. Or you can use a data attribute instead of id.