React Native Performance Optimization and Profiling

#reactnative Performance Optimization and Profiling

  • State of React Native performanceReact per default re-renders a component every time its parent receives new props or updates its state, that’s one of many reasons why the React paradigm for building UI’s is superior.
  • Luckily many of the standard React Native components executes on a separate thread known as the main thread.
  • If you are offloading work from JavaScript to the native side prevent the bridge from becoming overloaded by monitoring how many times data are sent and received over the wire.
  • class Component extends React.Component { – renderSectionHeader = () = View style={…} /render() { – return ( – FlatList – {…this.props} – / – ) – } – }If you still consider to handle navigation on the JavaScript side or you are struggling with frame drops during animations.
  • class AfterInteractions extends React.Component {state = { interactions: true } – – componentDidMount() { – = { – this.setState({ interactions: false }) – }render() { – if (interactions) { – return null – } – return this.props.children – } – }Animations in React Native looks good and are easy to…

React Native is a popular technology for engineers who are looking for building mobile applications in a productive way without compromising on native performance. Devices today comes with multi core…
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React State From the Ground Up

#ReactJS State From the Ground Up #JavaScript

  • State, in React, is a plain JavaScript object that allows you keep track of a component’s data.
  • The initial state of the App component has been set to a state object which contains the key username, and its value using .
  • Initializing a component state can get as complex as what you can see here: – – An initialized state can be accessed in the method, as I did above.
  • Your component should look like this; – – A state can be passed as props from a parent to the child component.
  • This method will be used to update the state of the component.

As you begin to learn React, you will be faced with understanding what state is. State is hugely important in React, and perhaps a big reason you’ve looked into using React in the first place. Let’s take a stab at understanding what state is and how it works. What is State? State, in React, is a plain JavaScript
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React Tutorial: A Comprehensive Guide to learning React.js in 2018

  • These components are defined either in pure JavaScript or they can be defined in what the React team calls “JSX”.
  • The reason the React team went with this approach is because, since the virtual DOM is a JavaScript representation of the actual DOM, React can keep track of the difference between the current virtual DOM(computed after some data changes), with the previous virtual DOM (computed befores some data changes).
  • In more layman’s terms, because manipulating the actual DOM is slow, React is able to minimize manipulations to the actual DOM by keeping track of a virtual DOM and only updating the real DOM when necessary and with only the necessary changes.
  • The process looks something like this, – – Some user event which changes the state of your app → Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.
  • Signal to notify our app some data has changed→ Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.

Continue reading “React Tutorial: A Comprehensive Guide to learning React.js in 2018”

A Comprehensive Guide to React.js in 2018

  • These components are defined either in pure JavaScript or they can be defined in what the React team calls “JSX”.
  • The reason the React team went with this approach is because, since the virtual DOM is a JavaScript representation of the actual DOM, React can keep track of the difference between the current virtual DOM(computed after some data changes), with the previous virtual DOM (computed befores some data changes).
  • In more layman’s terms, because manipulating the actual DOM is slow, React is able to minimize manipulations to the actual DOM by keeping track of a virtual DOM and only updating the real DOM when necessary and with only the necessary changes.
  • The process looks something like this, – – Some user event which changes the state of your app → Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.
  • Signal to notify our app some data has changed→ Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.

This is the original guide for learning to build apps with React.js. Recently upgraded to support React 16.3 and friends.
Continue reading “A Comprehensive Guide to React.js in 2018”

React Tutorial: A Comprehensive Guide to learning React.js in 2018

  • These components are defined either in pure JavaScript or they can be defined in what the React team calls “JSX”.
  • The reason the React team went with this approach is because, since the virtual DOM is a JavaScript representation of the actual DOM, React can keep track of the difference between the current virtual DOM(computed after some data changes), with the previous virtual DOM (computed befores some data changes).
  • In more layman’s terms, because manipulating the actual DOM is slow, React is able to minimize manipulations to the actual DOM by keeping track of a virtual DOM and only updating the real DOM when necessary and with only the necessary changes.
  • The process looks something like this, – – Some user event which changes the state of your app → Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.
  • Signal to notify our app some data has changed→ Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.

Continue reading “React Tutorial: A Comprehensive Guide to learning React.js in 2018”

Beyond React 16: Time Slicing and Suspense API

  • The latest release of ReactJS which is React 16 ships with a lot of features such as , , , and many others.
  • A sneak peek into new features coming to React was demoed by the creator of Redux and React core team member, Dan Abramov at JSConf Iceland, 2018.
  • Making it easier for developers to build great user experiences using ReactJS has always been the goal of the ReactJS team.
  • Time-slicing allows ReactJS, which now runs on React Fiber, to split computations of updates on children components into chunks during idle callbacks and rendering work is spread out over multiple frames.
  • Besides the steps shown in this section, the guide also shows: – – I’m overwhelmed by the engagement of React core team members with members of the JavaScript community in landing new features in React.

Time Slicing, Suspense and the Fetcher API are new features and concepts that will land soonest in stable releases of ReactJS. Learn how they work.
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A first look at Async React + Apollo – Apollo GraphQL

A first look at #Async #reactjs + #Apollo – Apollo #GraphQL  #javascript

  • A first look at Async React + ApolloThe suspense was killing us, so we built async React Apollo!Like many members of the React community, the Apollo team eagerly woke up at 5:00 AM to catch Dan Abramov’s talk on the future of React at JSConf Iceland.
  • Showcasing two outstanding demos, Dan illustrated some of async React’s new features such as time slicing and suspense.
  • Thanks to James Baxley III, we shipped a prerelease of React Apollo 3.0 that’s 100% strict mode compliant, which is essential in order for your library to be async compatible.
  • Here’s a step-by-step breakdown from Andrew about how it works: – Let’s look at how Dan implemented data fetching with suspense in the I/O demo from his talk: – Fetching data in render! 😮Under the hood, the createFetcher function uses React’s new cache implementation called simple-cache-provider in order to suspend the…
  • Aside from setting the asyncMode flag on your Query component, you’ll notice not much has changed with how you build Apollo apps in an async React world vs. how you build them today.

Like many members of the React community, the Apollo team eagerly woke up at 5:00 AM to catch Dan Abramov’s talk on the future of React at JSConf Iceland. With big mugs of coffee in hand, we glued…
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React Components Explained – codeburst

  • Something like thisimport React from ‘react’;class MyComponent extends React.Component { render () { return div This is a component /div }}class MyOtherComponent extends React.Component { render () { return ( div MyComponent / /div ) }}This way you are able to compose more complex and useful user interface for your…
  • Component’s render method return JSX which then use to create real HTML output which will be rendered in the browser.The interesting Thing about render method is that it runs every time when your component State or Props updates.
  • Let me show you a exampleimport React from ‘react’;class MyComponent extends React.Component { constructor(props) { super(props); this.state = { name: “Manoj” }; } render () { return div My name is {this.state.name} /div }}// if we render this component the output will beMy name is ManojIgnore the super(props) (out of…
  • Let’s see an example.class MyComponent extends React.Component { constructor(props) { super(props); this.state = { name: “Manoj” }; this.changeName = this.changeName.bind(this); } changeName () { this.setState({ name: “Your Name” }); } render () { return div onClick={this.changeName} My name is {this.state.name} /div }}In the above code we are telling our React…
  • You can run this code on jsFiddle here.PropsVisualise props as options that can be passed to a component to customize its functionality.For example, I have a heading component which renders a heading with subtitle.class MyHeading extends React.Component { render () { return div h1This is a heading/h1 pSubtitle/p /div }}If…

The simplest library I ever used in my life is React. As you know React is based upon component design. Everything in React is a component which makes it easy to reuse components frequently. You can…
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React v16.2.0: Improved Support for Fragments

React 16.2 is here:  - the biggest addition is support for

  • To make the authoring experience as convenient as possible, we’re adding syntactical support for fragments to JSX: – – In React, this desugars to a element, as in the example from the previous section.
  • Support for fragment syntax in JSX will vary depending on the tools you use to build your app.
  • Support for JSX fragments is available in Babel v7.0.0-beta.31 and above!
  • Upgrade to the latest TypeScript with the command: – – Flow support for JSX fragments is available starting in version 0.59!
  • A big thanks to everyone who filed issues, contributed to syntax discussions, reviewed pull requests, added support for JSX fragments in third party libraries, and more!

React 16.2 is now available! The biggest addition is improved support for returning multiple children from a component’s render method. We call this feature fragments:
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Learning React.js: Getting Started and Concepts ― Scotch

  • — React Code Goes Here — – – /script – /body – /html – In React, components mount to an element, so in this example we can use the div myDiv as it’s parent container.
  • These attributes are available in our component as this.props and can be used in our render method to render dynamic data: – var MyComponent = React.createClass({ – render: function(){ – return ( – h1Hello, {this.props.name}!
  • Below, see how we can set our component’s state: – var MyComponent = React.createClass({ – getInitialState: function(){ – return { – count: 5 – } – }, – render: function(){ – return ( – h1{this.state.count}/h1 – ) – } – }); – – Events – React also has a built…
  • Lets make our count increment below using events: – /** @jsx React.DOM */ – – var Counter = React.createClass({ – incrementCount: function(){ – this.setState({ – count: this.state.count + 1 – }); – }, – getInitialState: function(){ – return { – count: 0 – } – }, – render: function(){ -…
  • == -1; – }); – this.setState({items: updatedList}); – }, – getInitialState: function(){ – return { – initialItems: [ – “Apples”, – “Broccoli”, – “Chicken”, – “Duck”, – “Eggs”, – “Fish”, – “Granola”, – “Hash Browns” – ], – items: [] – } – }, – componentWillMount: function(){ – this.setState({items: this.state.initialItems})…

Today we are going to kick off the first installment in a new series of tutorials, Learning React, that will focus on becoming proficient and effective with Facebook’s React library. Before we start building anything meaningful, its important that we cover some base concepts first, so lets get this party started.
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