Object.keys preserves key order. I’ve never (will never) depend on, but good to know …

  • However, this breaks down in one situation: if you have two sets of children that you need to reorder, there’s no way to put a key on each set without adding a wrapper element.
  • That is, if you have a component such as: – – The children will unmount and remount as you change the prop because there aren’t any keys marked on the two sets of children.
  • To solve this problem, you can use the add-on to give keys to the sets of children.
  • Instead of creating arrays, we write: – – The keys of the passed object (that is, and ) are used as keys for the entire set of children, and the order of the object’s keys is used to determine the order of the rendered children.
  • Note also that we’re relying on the JavaScript engine preserving object enumeration order here, which is not guaranteed by the spec but is implemented by all major browsers and VMs for objects with non-numeric keys.

In most cases, you can use the key prop to specify keys on the elements you’re returning from render. However, this breaks down in one situation: if you have two sets of children that you need to reorder, there’s no way to put a key on each set without adding a wrapper element.
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…”

How to use React’s Provider Pattern

How to use React's Provider Pattern  #reactjs #webdev

  • Therefore you could use React’s context to give every component access to the colored theme.
  • That way every component that needs to be styled according to the colored theme could get the necessary information from React’s context object.
  • You have the Provider component that makes properties accessible in React’s context and components that consume the context.
  • This Provider component uses React’s context to pass down the state implicitly.
  • You provide the state to your component as props, the component wraps it into React’s context and all child components can access the state by using a higher order component such as from the react-redux library.

This article gives you a walkthrough for React’s provider pattern. After reading it, you should be able to implement…
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Understanding React — Component life-cycle – Bartosz Szczeciński – Medium

Understanding #ReactJS: Component life-cycle

  • DOupdate state via this.setStateperform last minute optimizationcause side-effects (AJAX calls etc.) in case of server-side-rendering onlyDON’Tcause any side effects (AJAX calls etc.) on client function will be called in each update life-cycle caused by changes to props (parent component re-rendering) and will be passed an object map of all the…
  • == this.props.myProps) { // nextProps.myProp has a different value than our current prop // so we can perform some calculations based on the new value }}Due to the fact that with React Fiber (post 16 beta) this function might be called multiple times before the renderfunction is actually called it…
  • == this.props.myProp) { // this.props.myProp has a different value // we can perform any operations that would // need the new value and/or cause side-effects // like AJAX calls with the new value – this.props.myProp }}DOcause side effects (AJAX calls etc.)DON’Tcall this.setState as it will result in a re-renderAn exception…
  • Please take extra care to prevent against updating if the value did not in fact change as it might result in a render errorInfo)A new addition in React 16 — this life-cycle method is special in way that it can react to events happening in the child component, specifically to any uncaught…
  • Please take extra care to prevent against updating if the value did not in fact change as it might result in a render loop.componentWillUnmountUse this function to “clean up” after the component if it takes advantage of timers (setTimeout, setInterval), opens sockets or performs any operations we need to close…

React provides developers with many methods or “hooks” that are called during the life-cycle of an component, which allows us to update the UI and application state. Knowing when to use which of them…
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Modern React with Redux

  • Course Last Updated 4/24/17 for React Router v4 and Redux Form v6!
  • Mastering React and Redux can get you a position in web development or help you build that personal project you’ve been dreaming of.
  • This course will get you up and running quickly, and teach you the core knowledge you need to deeply understand and build React components and structure applications with Redux.
  • If you are new to React and Redux, or if you’ve been working to learn it but sometimes feel like you still don’t quite ‘get it’, this is the React course for you!
  • I’ve built the course that I would have wanted to take when I was learning React and Redux.

Master the fundamentals of React and Redux with this tutorial as you develop apps supported by NPM, Webpack, and ES6
Continue reading “Modern React with Redux”

Modern React with Redux

  • Course Last Updated 4/24/17 for React Router v4 and Redux Form v6!
  • Mastering React and Redux can get you a position in web development or help you build that personal project you’ve been dreaming of.
  • This course will get you up and running quickly, and teach you the core knowledge you need to deeply understand and build React components and structure applications with Redux.
  • If you are new to React and Redux, or if you’ve been working to learn it but sometimes feel like you still don’t quite ‘get it’, this is the React course for you!
  • I’ve built the course that I would have wanted to take when I was learning React and Redux.

Master the fundamentals of React and Redux with this tutorial as you develop apps supported by NPM, Webpack, and ES6
Continue reading “Modern React with Redux”

8 things to learn in React before using Redux

8 things to learn in #ReactJS before using #Redux:

  • A component can manage a whole lot of state, pass it down as props to its child components and pass a couple of functions along the way to enable child components to alter the state in the parent component again.
  • Component A is the only component that manages local state but passes it down to its child components as props.
  • In addition, it passes down the necessary functions to enable B and C to alter its own state in A.

    Now, half of the local state of component A is consumed as props by component C but not by component B.

  • When you lift the local state management down to component C, all the necessary props don’t need to traverse down the whole component tree.
  • When a library such as Redux “connects” its state managements layer with React’s view layer, you will often run into a higher order component that takes care of it (connect HOC in react-redux).

Facts about React that should be known before using Redux (or MobX). Most important: Learn React first, then opt-in Redux…
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Modern React with Redux

  • Course Last Updated 4/24/17 for React Router v4 and Redux Form v6!
  • Mastering React and Redux can get you a position in web development or help you build that personal project you’ve been dreaming of.
  • This course will get you up and running quickly, and teach you the core knowledge you need to deeply understand and build React components and structure applications with Redux.
  • If you are new to React and Redux, or if you’ve been working to learn it but sometimes feel like you still don’t quite ‘get it’, this is the React course for you!
  • I’ve built the course that I would have wanted to take when I was learning React and Redux.

Master the fundamentals of React and Redux with this tutorial as you develop apps supported by NPM, Webpack, and ES6
Continue reading “Modern React with Redux”