Develop Reference

Recursively structure array of objects : ReactJS

I am trying to render an array as a nested tree which can go up-to n levels. Basically I have an JSX that depicts parent and children. Based on if the node is parent or child , I need to render the tree by attaching classname.
JSX of the parent looks like:
<div className="level-0 group">
<div className="details-holder">
<span className="item-text">{name}</span>
</div>
</div>
JSX of the children look like:
<div className="level-1 leaf">
<span className="line" />
<div className="details-holder">
<span className="item-text">{name}</span>
</div>
</div>
<div className="level-2 leaf">
<span className="line" />
<div className="details-holder">
<span className="item-text">{name}</span>
</div>
</div>
These JSX needs to rendered dynamically based on the array of the objects with the follolwing structure
[{
"name": "abc",
"className": "level-0 group",
"children": [{
"name": "abc.xyz",
"className": "level-1 leaf",
"children": [{
"className": "level-2 leaf",
"name": "abc.xyz.pqr",
"children": []
}]
}]
}]
So ideally the parent should have level-0 group class, children level-1 leaf , grandchildren level-2 leaf and so on.
Code that I tried is below, but how would I do it dynamically
return(
{ data.map(item => {
<>
<div className=`${item.className}`>
<div className="details-holder">
<span className="item-text">{item.name}</span>
</div>
</div>
<div className={`${item[0].children[0].className`}>
<span className="line" />
<div className="details-holder">
<span className="item-text">{item[0].children[0].name}</span>
</div>
</div>
<div className={`${item[0].children[1].className`}>
<span className="line" />
<div className="details-holder">
<span className="item-text">{item[0].children[1].name}</span>
</div>
</div>
</>
}
}
)
Thanks for the help.

Please check this if it's work for you. It more in modular form which help you to update the parent and child HTML fragment separately.
const Parent = (item) => (
<div className={`${item.className}`}>
<div className="details-holder">
<span className="item-text">{item.name}</span>
</div>
</div>
);
const Child = (item) => (
<div className={`${item.className}`}>
<span className="line" />
<div className="details-holder">
<span className="item-text">{item.name}</span>
</div>
{item.children.map((ch) => (
<Child {...ch} />
))}
</div>
);
export default function App() {
return (
<div className="App">
{data.map((item) => (
<>
<Parent {...item} />
{item.children.map((ch) => (
<Child {...ch} />
))}
</>
))}
</div>
);
}

This is actually very simple if you implement the recursion inside the component. Just pass children as data into the same component calling itself.
const Tree = (props) => {
return <>
{
props.data.map((item) => {
return <div className = {item.className} > {
(props.level !== 0) && < span className = "line" />
} <div className = "details-holder" >
<span className = "item-text" > {name} </span> </div> {
props.data.children.map(() => <Tree data={item.children} level={props.level + 1} > )
} </div>
})
}
</>
}
<Tree data={data} level={0} />

How to horizontalize react js component?

I created app to map all card components on a page. But components are shown vertically. I need to show 3 components per row. How can I show it like that? Here is my code.
const[item, setItem] = useState([]);
function addItem(newItem){ //This addItem Part is working.
setItem(prevItems =>{
return [...prevItems, newItem]
});
}
return(<div className="container">
<div className="row">
<div className="col-lg-4" style={{cursor: "pointer"}}>
<AddCard />
</div>
<div style={{cursor: "pointer"}}>
{item.map((items, index)=>{
return(
<div className="col-lg-4" >
<ItemCard
key={index}
id={index}
title={items.title}
description={items.description}
/>
</div>
)
})}
</div>
</div>)

You can use display:"flex" on the container
const[item, setItem] = useState([]);
function addItem(newItem){ //This addItem Part is working.
setItem(prevItems =>{
return [...prevItems, newItem]
});
}
return(<div className="container">
<div className="row">
<div className="col-lg-4" style={{cursor: "pointer"}}>
<AddCard />
</div>
<div style={{cursor: "pointer", display:"flex"}}>
{item.map((items, index)=>{
return(
<div className="col-lg-4" >
<ItemCard
key={index}
id={index}
title={items.title}
description={items.description}
/>
</div>
)
})}
</div>
</div>)

Use flexboxes, as React lets you create components, so we can style them just like HTML elements with flexboxes.
Example :
.flexbox-container {
display: flex;
flex-direction: row;
}
<div class="flexbox-container">
<div>Element1</div>
<div>Element2</div>
<div>Element3</div>
</div>

How Can I change the property of components of React?

I am new to React and recently started working on it. I know that we cannot change the components properties using the props.
I want to know how can we change the properties of Component?
Below is my code:
Courses.jsx
function Courses(){
return (
<div className="courses">
<h1>Ongoing Courses</h1>
<div className="row">
{CourseData.map((value,index)=>{
return (
<div className="col-md-3">
<Card title={value.title} completed={value.completed} content={value.content} value="Resume !" key={index} id={index} />
</div>
);
})}
</div>
</div>
);
}
Here above i am having a Array of Data named as courseData, I am mapping it on a Card component.
Card.jsx:
function Card(props){
function handleClick(){
}
return (
<div className="card">
<div className="card-body">
<h2 className="card-title">{props.title}</h2>
{props.content}
<br/>
<button className="btn btn-danger" > {props.value}</button>
</div>
</div>
);
}
the CourseData has following properties :
courseData : [{
key,
title,
completed
content}]
I simply want that when ever the button present is card gets clicked then the completed attribute of courseData changed to some different value that is passed through the props .
I have tried a lot but not able to do .
Any help regarding this will be helpful for me .
courseData.jsx:
const notes = [{
key: 1,
title: "some Text",
completed:false,
content: "some Text"
},
{
key: 2,
title: "some Text",
completed:false,
content: "some Text"
}]
export default notes;

Add CourseData to the state of the Courses component. Then add a method to adjust the data there. Pass the method throught props that will be called when clicking button in the Card component:
function Courses() {
const [courseData, setCourseData] = useState(CourseData);
const updateCourseData = (index) => {
courseData.splice(index, 1);
setCourseData(courseData);
}
return (
<div className="courses">
<h1>Ongoing Courses</h1>
<div className="row">
{courseData.map((value,index)=>{
return (
<div className="col-md-3">
<Card title={value.title} updateCourseData={updateCourseData} completed={value.completed} content={value.content} value="Resume !" key={index} id={index} />
</div>
);
})}
</div>
</div>
);
}
in the Card.jsx:
<button onClick={() => props.updateCourseData(props.id)} className="btn btn-danger" > {props.value}</button>

function Courses(){
const [coursesData, setCoursesData] = useState(CourseData)
return (
<div className="courses">
<h1>Ongoing Courses</h1>
<div className="row">
{coursesData.map((value,index)=>{
return (
<div className="col-md-3">
<Card coursesData={coursesData} setCoursesData={setCoursesData} title={value.title} completed={value.completed} content={value.content} value="Resume !" key={index} id={index} />
</div>
);
})}
</div>
</div>
);
function Card({id,title,value,content,coursesData,setCoursesData }){
function handleClick(e){
e.preventDefault()
setCoursesData(coursesData => {
const data = coursesData
data.splice(id,1,{
title: title,
completed: value,
content: content,
key: id
})
return data
})
}
return (
<div className="card">
<div className="card-body">
<h2 className="card-title">{title}</h2>
{content}
<br/>
<button onClick={handleClick} className="btn btn-danger">{value}</button>
</div>
</div>
);

Cards inside the grid-container: each child in a list should have a unique "key" prop

What I`m doing wrong?It also says: "Check the render method of Card" , which is here:
<div className="grid-container">
{pokemonData.map((pokemon, i) => {
console.log(pokemon.id) // unique numbers are here
return <Card key={pokemon.id} pokemon={pokemon} />
})}
</div>
Card component itself:
function Card({ pokemon }) {
return (
<div className="card">
<div className="card__image">
<img src={pokemon.sprites.front_default} alt="Pokemon" />
</div>
<div className="card__name">
{pokemon.name}
</div>
<div className="card__types">
{
pokemon.types.map(type => {
return (
<div className="card__type" style={{backgroundColor: typeColors[type.type.name]}}>
{type.type.name}
</div>
)
})
}
</div>
<div className="card__info">
<div className="card__data card__data--weight">
<p className="title">Weight:</p>
<p>{pokemon.weight}</p>
</div>
<div className="card__data card__data--height">
<p className="title">Height:</p>
<p>{pokemon.height}</p>
</div>
<div className="card__data card__data--ability">
<p className="title">Abilities:</p>
{/* {console.log(pokemon.abilities)} Temporary for dev puprose */}
{pokemon.abilities.map(ability => <p>{ability.ability.name}</p>
)}
</div>
</div>
</div>
);
}
export default Card;

You can use the index of the array may be your data is having some kind of duplicate. It is recommended that you pass a key prop whenever you are returning a list.
<div className="grid-container">
{pokemonData.map((pokemon, i) => {
console.log(pokemon.id) // unique numbers are here
return <Card key={i} pokemon={pokemon} />
})}
</div>
Equally, check this segment of card components.
{
pokemon.types.map((type,i) => {
return (
<div key={i} className="card__type" style={{backgroundColor:
typeColors[type.type.name]}}>
{type.type.name}
/div>
)
})
}
And
<div className="card__data card__data--ability">
<p className="title">Abilities:</p>
{/* {console.log(pokemon.abilities)} }
{pokemon.abilities.map((ability, i) => <p key={i}>{ability.ability.name}
</p>
)}
</div>

Previous answer will solve your problem. However, for your info, I would also like to add here.
For React a key attribute is like an identity of a node/element/tag which helps React to identify each item in the list and apply reconciliation correctlyon each item. Without a key React will render your component but may cause issue when you re-order your list.
React recommends to use id of the data instead of index number. However, if your list does not re-orders/ sorts or do not have id then you can use index.
You can read more here:
https://reactjs.org/docs/lists-and-keys.html

Change this:
<div className="card__types">
{
pokemon.types.map(type => {
return (
<div className="card__type"
style={{backgroundColor:typeColors[type.type.name]}}
>
{type.type.name}
</div>
)
})
}
</div>
to:
<div className="card__types">
{
pokemon.types.map((type, key) => {
return (
<div key={key} className="card__type"
style={{backgroundColor:typeColors[type.type.name]}}
>
{type.type.name}
</div>
)
})
}
</div>
and:
{pokemon.abilities.map(ability => <p>{ability.ability.name}</p>
to:
{pokemon.abilities.map((ability,key) => <p key={key} >{ability.ability.name}</p>

Pass value to a modal in jsx map

I have a map that render few items. How can I pass params like name of the item, id of the item etc to the modal component?
render(){
return(
<div>
<Modal
isOpen={this.state.OpenDeleteModal}
confirmationTitle={`Delete item`}
confirmationCancel={'No'}
confirmationSuccess={'Yes'}
closeModal={this.closeModal}
successModal={this.successModal}
>
<p className="center">Are you sure you want to delete this item?</p>
</Modal>
<div className="wrapper">
{map(items, obj =>
<div key={obj._id} className="panel-body">
<div className="row">
<h2 className="title">{obj.name}</h2>
<a onClick={()=> this.setState({OpenDeleteModal:true})}>Delete</a>
</div>
</div>
)}
</div>
</div>
)
}
I only can think of put the obj._id in the tag as custom attribute and when user click on delete it change the state of the selectedItem, pass it through props.

One simple solution is to remember for which item you have opened the modal. Something like below. Set the selected item when you open the modal. During delete, fetch it from state and delete it.
render(){
return(
<div>
<Modal
isOpen={this.state.OpenDeleteModal}
confirmationTitle={`Delete item`}
confirmationCancel={'No'}
confirmationSuccess={'Yes'}
closeModal={this.closeModal}
successModal={this.successModal}
>
<p className="center">Are you sure you want to delete this item?</p>
</Modal>
<div className="wrapper">
{map(items, obj =>
<div key={obj._id} className="panel-body">
<div className="row">
<h2 className="title">{obj.name}</h2>
<a onClick={()=> this.setState({OpenDeleteModal:true, selectedItem: obj._id})}>Delete</a>
</div>
</div>
)}
</div>
</div>
)
}
UPDATE: Make sure to clear the selectedItem after you close the modal.

A modal can access the state of the react component, you can store the information of the selected link in state
storeInformation(item) {
this.setState({OpenDeleteModal:true,
selectedId: item.id
selectedName: item.name
})
}
render(){
return(
<div>
<Modal
isOpen={this.state.OpenDeleteModal}
confirmationTitle={`Delete item`}
confirmationCancel={'No'}
confirmationSuccess={'Yes'}
closeModal={this.closeModal}
successModal={this.successModal}
>
<p className="center">Are you sure you want to delete this item?</p>
<div>Name is: {this.state.selecteName}</div>
</Modal>
<div className="wrapper">
{map(items, obj =>
<div key={obj._id} className="panel-body">
<div className="row">
<h2 className="title">{obj.name}</h2>
<a onClick={()=> this.storeInformation(obj)}>Delete</a>
</div>
</div>
)}
</div>
</div>
)
}