I have built a component in React which is supposed to update its own style on window scroll to create a parallax effect. The component render method looks like this: function() { let style = { transform: ‘translateY(0px)’ }; window.addEventListener(‘scroll’, (event) => { let scrollTop = event.srcElement.body.scrollTop, itemTranslate = Math.min(0, scrollTop/3 – 60); style.transform = … Read more
I’m creating a react.js application with flux architecture and I am trying figure out where and when a request for data from the server should be made. Is there a any example for this. (Not TODO app!) 6 Answers 6
Came to know that from React v15.3.0, we have a new base class called PureComponent to extend with PureRenderMixin built-in. What I understand is that, under the hood this employs a shallow comparison of props inside shouldComponentUpdate. Now we have 3 ways to define a React component: Functional stateless component which doesn’t extend any class … Read more
I’m expecting state to reload on props change, but this does not work and user variable is not updated on next useState call, what is wrong? function Avatar(props) { const [user, setUser] = React.useState({…props.user}); return user.avatar ? (<img src={user.avatar}/>) : (<p>Loading…</p>); } codepen 6 Answers 6
I am building a small react app and my local images won’t load. Images like placehold.it/200×200 loads. I thought maybe it could be something with the server? Here is my App.js import React, { Component } from ‘react’; class App extends Component { render() { return ( <div className=”home-container”> <div className=”home-content”> <div className=”home-text”> <h1>foo</h1> </div> … Read more
I am currently going through the React-Native tutorials. I began with the Getting Started tutorial, where I made a new react native project and successfully managed to run the project on my device. I then started the Props tutorial, I copied the code snippet and tried to run the project again and had the following … Read more
I just start working on a React project with TypeScript and ask myself what should I do with regular class files? Should I use .ts or .tsx files and then I couldn’t find any reason to do not using .tsx file all the times even when it’s not a React project! Is there any reason … Read more
In React 16.2, improved support for Fragments has been added. More information can be found on React’s blog post here. We are all familiar with the following code: render() { return ( // Extraneous div element 🙁 <div> Some text. <h2>A heading</h2> More text. <h2>Another heading</h2> Even more text. </div> ); } Yes, we need … Read more
class PlayerControls extends React.Component { constructor(props) { super(props) this.state = { loopActive: false, shuffleActive: false, } } render() { var shuffleClassName = this.state.toggleActive ? “player-control-icon active” : “player-control-icon” return ( <div className=”player-controls”> <FontAwesome className=”player-control-icon” name=”refresh” onClick={this.onToggleLoop} spin={this.state.loopActive} /> <FontAwesome className={shuffleClassName} name=”random” onClick={this.onToggleShuffle} /> </div> ); } onToggleLoop(event) { // “this is undefined??” <— here this.setState({loopActive: … Read more
What are controlled components and uncontrolled components in ReactJS? How do they differ from each other? 5 Answers 5
