I'm learning React.js.
I have this code:
const articles = Object
.keys(this.state.articles)
.map(key => <ArticleThumb key={key} details={this.state.articles[key]} />)
;
return (
<div className="container">
<div className="row">
{ articles }
</div>
</div>
)
Assuming I have 6 items, here is the code after rendering:
<div className="container">
<div className="row">
<div id="item1"></div>
<div id="item2"></div>
<div id="item3"></div>
<div id="item4"></div>
<div id="item5"></div>
<div id="item6"></div>
</div>
</div>
But I want to have only 3 items per line like this:
<div className="container">
<div className="row">
<div id="item1"></div>
<div id="item2"></div>
<div id="item3"></div>
</div>
<div className="row">
<div id="item4"></div>
<div id="item5"></div>
<div id="item6"></div>
</div>
</div>
What is the best way to do this?
The easy answer is to use something like lodash's chunk function https://lodash.com/docs/4.17.4#chunk
However, if you are not using npm and or do not want to add additional dependencies you are going to have to use a good old fashioned javascript for loop to perform the grouping you need.
With the markup you have you could do it via css:
.container {
display: flex;
flex-wrap: wrap;
}
.row {
width: 33%;
box-sizing: border-box;
}
I made a ArticleGrid component:
class ArticleGrid extends Component {
render() {
let articlesRows = Object
.keys(this.props.rows)
.map(key => <ArticleRow key={key} articles={this.props.rows[key]} />)
;
return (
<div id="articles" className="container">
{articlesRows}
</div>
);
}
}
export default ArticleGrid;
A ArticleRow component:
class ArticleRow extends Component {
render() {
let articles = Object
.keys(this.props.articles)
.map(key => <ArticleThumb key={key} details={this.props.articles[key]} />)
;
return (
<div className="row">
{articles}
</div>
);
}
}
export default ArticleRow;
I used lodash's chunk and values function (ty Deadron) and it's done:
let articles = _.values(this.state.articles);
let articlesRows = _.chunk(articles, 3);
return (<ArticleGrid rows={articlesRows} />);
Related
I am writing a simple blog component in React. The component get the post from a second file and renders the content and the hashtags with map (in particular two nested map). I was trying to create a part in which the hashtag are highlighted when clicked, and hence I was following the snippet of the answer to this question. The fact is that it is not working and in particular what it is not working is the binding through bind (checked with console.log output)
class Blog extends React.Component {
state= {
open: {}
}
handleClick = (k) => {
let linkOpenState = true;
if (this.state.open.hasOwnProperty(k)) {
linkOpenState = !this.state.open[k];
}
this.setState({ open: { [k]: linkOpenState } })
}
render(){
return(
posts.map(i=>(
<div class="box">
<article class="media">
<div class="media-content">
<div class="content">
<h1 class="title">{i.title}</h1>
<p>
{i.content}
</p>
</div>
<div class="tags">
{i.hash.map(k=>(<span id={k} onClick={this.handleClick.bind(this,k)} class={this.state.open[k]? "tag is-primary" : "tag"} >{k}</span>))}
</div>
</div>
</article>
</div>))
)
}
}
export default Blog
Anyone has an idea of what is wrong there? Is it the nested map a problem for the bind?
React expects a single element as a return. You can solve this by wrapping the return in a fragment as <React.Fragment> or <>.
Also, you don't need to bind an arrow function(handleClick when mapping i.hash).
render(){
return(
<>
posts.map(i=>(
<div class="box">
<article class="media">
<div class="media-content">
<div class="content">
<h1 class="title">{i.title}</h1>
<p>
{i.content}
</p>
</div>
<div class="tags">
{i.hash.map(k=>(<span key={k} id={k} onClick={() => this.handleClick(k)} class={this.state.open[k]? "tag is-primary" : "tag"} >{k}</span>))}
</div>
</div>
</article>
</div>))
</>)}}
You don't need to bind the arrow function.
Also, you need to pass unique key to elements when used inside map, you can use index as a key but if you are mutating the array then use some id or hash or anything which will be unique.
class Blog extends React.Component {
state= {
open: {}
}
handleClick = (k) => {
let linkOpenState = false;
if (this.state.open.hasOwnProperty(k)) {
linkOpenState = this.state.open[k];
}
this.setState({ open: { [k]: linkOpenState } })
}
render(){
return(
posts.map((i, index)=>(
<div class="box" key={i.id || index}>
<article class="media">
<div class="media-content">
<div class="content">
<h1 class="title">{i.title}</h1>
<p>
{i.content}
</p>
</div>
<div class="tags">
{i.hash.map(k=>(<span key={k} id={k} onClick={() => this.handleClick(k)} class={this.state.open[k]? "tag is-primary" : "tag"} >{k}</span>))}
</div>
</div>
</article>
</div>))
)
}
}
export default Blog
I have a react code (just a snippet, its not a complete code) as shown below which shows the list of programs on the webpage. Line A in the react code below renders all list of program on the webpage.
react code:
const renderPrograms = () => {
return programs.map((program, index)=>{
return (
<a href={program.url} key={index}>
<div className="program" >
<div class="hello-world">{program.name}</div>
</div >
</a>
)
})
}
return(
<div class="parent-div">
<div className ="pqr-xyz">
<h5>Hello World</h5>
</div>
<div className ="abc-def">
<h5>Programs</h5>
{programs && renderPrograms()} {/*Line A*/}
</div>
</div>
)
The above react code renders the following html code at runtime:
<div class="parent-div">
<div className ="pqr-xyz">
<h5>Hello World</h5>
</div>
<div class="abc-def">
<h5>Programs</h5>
<a href="https://www.google.com/">
<div class="program">
<div class="hello-world">TYUV</div>
</div>
</a>
<a href="https://www.twitter.com/">
<div class="program">
<div class="hello-world">SGHS</div>
</div>
</a>
</div>
</div>
Problem Statement:
When Line A does not render anything, my div (<div className ="abc-def">) will look like this at run time:
<div class="abc-def">
<h5>Programs</h5>
</div>
I am wondering what changes I need to make in my react code above so that when Line A doesn't render anything then <div class="abc-def"><h5>Programs</h5></div> should not display on the webpage.
They should be part of the condition:
return(
programs.length > 0 && <div className ="abc-def">
<h5>Programs</h5>
{renderPrograms()}
</div>
)
I changed the condition to check for length, otherwise you'll get a 0 instead of nothing, when empty
Try change this lines:
<div className ="abc-def">
<h5>Programs</h5>
{programs && renderPrograms()} {/*Line A*/}
</div>
into this:
{ programs && (
<div className ="abc-def">
<h5>Programs</h5>
{renderPrograms()} {/*Line A*/}
</div>
) }
Now without programs nothing is displayed.
You can try adding a className like this:
<div className={`abc-def ${programs.length ? "hidden" : ""}`}
Or from the parent componet, you can choose to not render this component with <div>
Instead of trying to hide it using CSS, you also can choose to not render it at all by returning nothing from your function
const RenderPrograms = ({ programs = [] }) => {
if (!programs.length) {
return []
}
return (
<div className="abc-def">
<h5>Programs</h5>
{programs.map((program, index) =>
<a href={program.url} key={index}>
<div className="program">
<div>{program.name}</div>
</div>
</a>
)}
</div>
)
}
ReactDOM.render(
<RenderPrograms />,
document.getElementById('react')
)
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>
<div id="react"></div>
You can try putting your class in a template string and using a ternary operator to display a certain class when some state value is true.
<div className={`${stateValue ? "name-of-class-with-hide" : "abc-def"}`}>
Here is a complete solution. All you need to do is move the <h5>Programs</h5> inside the condition and modify the condition slightly as shown in following snippet.
<div className ="abc-def">
{
programs.length > 0 && (
<div>
<h5>Programs</h5>
<RenderPrograms programs = {programs}/>
</div>
)
}
</div>
Note that I have modified the RenderPrograms function as well to accept arguments.
Following is a full snippet.
function RenderPrograms(props) {
return props.programs.map((program, index)=>{
return (
<a href={program.url} key={index}>
<div className="program" >
<div className="hello-world">{program.name}</div>
</div >
</a>
)
});
}
function MyApp() {
const programs=[
{name:'program 1', url: 'https://url1.com'},
{name:'program 2', url: 'url2'},
{name:'program 3', url: 'url3'},
];
const programs1 = []; // empty program list
return(
<div class="parent-div">
<h1>When programs list is not empty</h1>
{/*Above line is just for explanation -- you may remove it*/}
<div className ="pqr-xyz">
<h5>Hello World</h5>
</div>
<div className ="abc-def">
{
programs.length > 0 && (
<div>
<h5>Programs</h5>
<RenderPrograms programs = {programs}/>
</div>
)
}
</div>
{/*Below code is just for explanation -- you may remove it*/}
<hr />
<h1>When programs list is empty</h1>
<div className ="pqr-xyz">
<h5>Hello World</h5>
</div>
<div className ="abc-def">
{
programs1.length > 0 && (
<div>
<h5>Programs</h5>
<RenderPrograms programs = {programs1}/>
</div>
)
}
</div>
</div>
)
}
ReactDOM.render(
<MyApp />,
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"></div>
You need to move rendering of programs into RenderPrograms component. Make RenderPrograms component purelu functional and pass data to it via props (Instead of using function).
const RenderPrograms = ({ programs }) => {
let disp = programs.map((program, index) => {
return (
<a href={program.url} key={index}>
<div className="program">
<div class="hello-world">{program.name}</div>
</div>
</a>
);
});
return disp || <span />;
};
then use RenderPrograms to render programs in main component (One with logis for loading programs).
// let programs = [
// {
// url: "test1.com",
// name: "test1"
// },
// {
// url: "test2.com",
// name: "test2"
// }
// ];
let programs = [];
return (
<div className="App">
<div class="parent-div">
<div className="pqr-xyz">
<h5>Hello World</h5>
</div>
<div className="abc-def">
<h5>Programs</h5>
<RenderPrograms programs={programs} />
{/* {programs && renderPrograms()} Line A */}
</div>
</div>
</div>
);
You can play around with this sandbox
I'm trying to get the end result to look like, (following this example):
<style>
* {
box-sizing: border-box;
}
.column {
float: left;
width: 50%;
padding: 10px;
height: 300px;
}
.row:after {
content: "";
display: table;
clear: both;
}
</style>
<div class="row">
<div class="column">
<Component />
</div>
<div class="column">
<Component />
</div>
</div>
The problem is that I can't quite figure out how to do this in React. The original map function currently looks like:
<div className="main">
{
arrayOfComponents.map((({ name }), index) => (
<Component
key={`${index}-${name}`}
label={name}
/>
))
}
</div>
I've tried doing something like,
<div className="main">
{
arrayOfComponents.map((({ name }), index) => (
<div className={index % 2 === 0 ? 'row' : ''}>
<div className="column">
<Component
key={`${index}-${name}`}
label={name}
/>
</div>
</div>
))
}
</div>
But that didn't seem to work, and if it did, it seems messy. How can I go about this?
arrayOfComponents looks something like
const arrayOfComponents = [
{ name: 'abc', key: 'value1'},
{ name: 'def', key: 'value2' },
. . .
]
You just need to map over the array and return the Component wrapped in a div with className of column like this :
<div className="main">
<div className="row">
{
arrayOfComponents.map(({name},index) => (
<div className="column">
<Component
key={`${index}-${name}`}
label={name}
/>
</div>
))
}
</div>
</div>
* {
box-sizing: border-box;
}
/* Create two equal columns that floats next to each other */
.column {
float: left;
width: 50%;
padding: 10px;
}
/* Clear floats after the columns */
.row:after {
content: "";
display: table;
clear: both;
}
.bg{
background:orange;
border: 2px solid red;
margin: 0 auto 100px;
}
<div class="row bg">
<div class="column">
<h2>Column 1</h2>
<p>Some text..</p>
</div>
<div class="column">
<h2>Column 2</h2>
<p>Some text..</p>
</div>
</div>
<div class="bg">
<div class="column">
<h2>Column 1</h2>
<p>Some text..</p>
</div>
<div class="column">
<h2>Column 2</h2>
<p>Some text..</p>
</div>
</div>
Hope this helps !
If you specifically need additional row elements, You can use conditional rendering like this. This would create a new row after 2 columns.
<div className="main">
{
arrayOfComponents.map(({ name }, index) => index%2!=0?null:(
<div className="row">
<div className="column">
<Component
key={`${index}-${name}`}
label={name}
/>
</div>
{arrayOfComponents[index+1] && (
<div className="column">
<Component
key={`${index+1}-${arrayOfComponents[index+1].name}`}
label={arrayOfComponents[index+1].name}
/>
</div>
)}
</div>
))
}
</div>
You can use reduce for splitting your data:
const rows = arrayOfComponents.reduce((acc, rec, index) => {
if (index % 2 === 0) {
return [...acc, [rec]]
}
acc[acc.length - 1] = [...acc[acc.length - 1], rec]
return acc
}, [])
const Component = (props) => {
return <div>
<h2>{props.item.name}</h2>
<p>{props.item.key}</p>
</div>
}
const TodoApp = () => {
return rows.map((row, index)=>{
return <div key={index}>{
row.map((col) => <div className="column" key={col.name}><Component item={col}/></div>)
}</div>
})
}
See full example in playground: https://jsfiddle.net/denisstukalov/ut8x9Lkq/21/#&togetherjs=Q7jLIOHHOP
I'm trying to create a show/hide div for when my mouse enters and leaves the container. I was following this example here (https://upmostly.com/tutorials/react-onhover-event-handling-with-examples) but I've run into a problem when I hover my mouse over the 'delete-container' div, it disappears. This problem occurs because it takes the action onMouseLeave. Is there a way I can fix this or possibly make my solution better? Here is a demo of what is happening (https://i.gyazo.com/528d909625b6b3828325c4e62894d1c3.mp4).
import React, { useState } from 'react';
import axios from 'axios';
export default function JobInfo({ jobs_info }) {
const [isShown, setIsShown] = useState(false);
const changeBackground = (x) => {
x.target.style.backgroundImage =
'linear-gradient(to right, #4639a7, #78019c)';
};
const changeBackground2 = (x) => {
x.target.style.background = 'rgb(37, 45, 73)';
};
return (
<div className='row'>
<div
className='container'
onMouseEnter={() => setIsShown(true)}
onMouseLeave={() => setIsShown(false)}
>
<div className='row'>
<div className='job-title'>{jobs_info.title}</div>
</div>
<div className='row wrapper'>
<div className='category-title'>Category</div>
<div className='location-title'>Location</div>
<div className='type-title'>Type of Job</div>
<div className='creator-title'>Job Creator</div>
</div>
<div className='row wrapper'>
<div className='category'>{jobs_info.job_team.title}</div>
<div className='location'>
{jobs_info.job_location.title}
</div>
<div className='type'>{jobs_info.job_work_type.title}</div>
<div className='creator'>{jobs_info.user.name}</div>
</div>
</div>
<div
className='counter-container'
id='counter-container'
onMouseEnter={changeBackground}
onMouseLeave={changeBackground2}
>
Candidates <br />
{jobs_info.candidates_count}
</div>
{isShown && (
<div className='delete-container center'>
<ion-icon id='trash' name='trash'></ion-icon>
</div>
)}
</div>
);
}
The issue happens because delete-container is outside of the container hierarchy and hence mouseleave event is triggered on the container. Render the delete-container as a child of container and style it accordingly
return (
<div className='row'>
<div
className='container'
onMouseEnter={() => setIsShown(true)}
onMouseLeave={() => setIsShown(false)}
>
<div className='row'>
<div className='job-title'>{jobs_info.title}</div>
</div>
<div className='row wrapper'>
<div className='category-title'>Category</div>
<div className='location-title'>Location</div>
<div className='type-title'>Type of Job</div>
<div className='creator-title'>Job Creator</div>
</div>
<div className='row wrapper'>
<div className='category'>{jobs_info.job_team.title}</div>
<div className='location'>
{jobs_info.job_location.title}
</div>
<div className='type'>{jobs_info.job_work_type.title}</div>
<div className='creator'>{jobs_info.user.name}</div>
</div>
{isShown && (
<div className='delete-container center'>
<ion-icon id='trash' name='trash'></ion-icon>
</div>
)}
</div>
<div
className='counter-container'
id='counter-container'
onMouseEnter={changeBackground}
onMouseLeave={changeBackground2}
>
Candidates <br />
{jobs_info.candidates_count}
</div>
</div>
);
However you could simply use CSS hover event to show or hide the delete-container without the need for state after renderingdelete-containeras a child ofcontainer`
.scss
.container {
.delete-container {
display: none;
// other styles
}
&:hover {
.delete-container {
display: block;
}
}
// other styles
}
I am using bootstrap and I want to render 4 columns in row. However I do not know how many columns I will have, so it should work for any number of columns and also first column can be different react component then other columns.
What I want to achieve:
<div class="row">
<div class="col-md-3 component-type-1">...</div>
<div class="col-md-3 component-type-2">...</div>
<div class="col-md-3 component-type-2">...</div>
<div class="col-md-3 component-type-2">...</div>
</div>
<div class="row">
<div class="col-md-3 component-type-2">...</div>
<div class="col-md-3 component-type-2">...</div>
<div class="col-md-3 component-type-2">...</div>
<div class="col-md-3 component-type-2">...</div>
</div>
I tried something but did not managed to achieve what I want..
import chunk from 'lodash/chunk.js'
class Test extends React.Component {
render() {
let component1=null;
if (this.state.shouldBeComponent1) {
component1=<Component1 key="component1" />;
}
let items = [];
if (component1!=null) items.push(component1);
this.state.dataForComponents2.forEach((data) => {
items.push(<Component2 key={data.ID} />)
});
const rows = chunk(items, 4);
let pageBody=null;
if (items.length>0) {
pageBody=(
rows.map((row) => {
<div className="row">
{
row.map((item) => (
{item}
))
}
</div>})
);
}
return (
<div>
<div className="header">
///Other unreleated code
</div>
{pageBody}
</div>
);
}
Seems something wrong with your pageBody
Try this.
let pageBody= [];
if (items.length>0) {
rows.forEach((row, idx) => {
pageBody.push
(
<div key={idx} className="row">
{row}
</div>
)}
);
}
And example here