How and Why to Bind a Callback Function in React Components

How and Why to Bind a Callback Function in #reactjs Components  #javascript

  • If you ask yourself, why you even have to bind callback functions and when you actually have to do this, this article is for you: Today we’re going to learn about binding the  keyword in React components.
  • Avoid binding by using the public class fields syntax, or bind your callbacks inside the constructor.
  • Another way to bind  is to do so in your parent component’s constructor by calling for your callback function: – – That’s it!
  • Instead of binding the callback function in your constructor, you can do so while passing it through a prop: – – Note: Whenever your component is re-rendered, returns a new function and passes it down your component tree.
  • Instead of using the public class field syntax, you could directly pass an arrow function down your props: – – Note: Like in the previous example, this creates a new callback each time your component is re-rendered and may cause unnecessary re-rendering of your component tree.

Why do we need to bind ‘this’? What’s the best way to bind a callback function in React components? Read about the why and how in this article and never worry about binding callbacks again!
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Introducing Immer: Immutability the easy way – Hacker Noon

  • The producer function receives one argument, the draft, which is a proxy to the current state you passed in.
  • The currentState will be untouched during this process.Because immer uses structural sharing, and our example producer above didn’t modify anything, the next state above is simply the state we started with.Let’s take look at what happens when we start modifying the draft in our producer.
  • It is not too bad in this simple case, but this process has to be repeated for every action, and on every level in which we want modify something.We have to make sure to return the existing state if the reducer doesn’t do anythingWith Immer, we only need to reason…
  • Both the original reducer and the new one behave exactly the same.No strings attachedThe idea to produce the next immutable state by modifying a temporarily draft isn’t new.
  • This will create a new function that will execute the producer when it’s passed in a state.

Immutable, structurally shared data structures are a great paradigm for storing state. Especially when combined with an event-sourcing architecture. However, there is a cost to pay. In a language…
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Playing with React Native Animations – Hacker Noon

Play with React Native animations:  #ReactJS #JavaScript

  • For the delay we’re using the delay that was passed to the component.
  • We want to actually use these files in our app – to do so replace index.ios.js and index.android.js with the following.
  • We’ll keep this very simple and create 10 data elements with a width between 0 and the screen width – this will all take place in app/index.js
  • In app/AnimatedBar.js we’ll just set some static styles and apply them to our view.
  • Then create an app/index.js and app/AnimatedBar.js and copy and paste the following into them to get started.

For my first post of the year I wanted to keep it light and experiment a little bit with the React Native Animated API. We’ll create a few bars that animate in and constantly change their size. Here…
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React.js pure render performance anti-pattern – Esa-Matti Suuronen – Medium

#ReactJS pure render performance anti-pattern:  by @EsaMatti #JavaScript

  • The Cell component was even more complicated and the app rendered multiple cells for each user.
  • const default = []; class Table extends PureComponent { render() { return (
    {this.props.items.map(i => )}

    ); } }

  • Originally I didn’t think that Reselect , library which is even mentioned in the official Redux docs, would be that important because I would rarely write that expensive map state functions for Redux connect() .
  • A new function is created with a new identity.
  • Pure render optimized React components can be extremely performant but it requires users to treat their data as immutable for it to work properly.

“React.js pure render performance anti-pattern” is published by Esa-Matti Suuronen
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Functional Components with React stateless functions and Ramda – Medium

Functional Components with React stateless functions and #Ramda:  #JavaScript #ReactJS

  • Finally create a main.js file and start rendering!
  • The components must not retain internal state, do not have backing instances, and do not have the component lifecycle methods.
  • The first time I read about react stateless components I wondered if I could R.compose such functions.
  • For now the only explanation needed is that, since we are using stateless components that are pure functions to their props , state must be managed elsewhere.
  • The simplified component API is intended for components that are pure functions of their props.

What you need to know:
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React.js pure render performance anti-pattern – Medium

React.js pure render performance anti-pattern:  by @EsaMatti #JavaScript #reactjs

  • The Cell component was even more complicated and the app rendered multiple cells for each user.
  • const default = []; class Table extends PureComponent { render() { return (
    {this.props.items.map(i => )}

    ); } }

  • Originally I didn’t think that Reselect , library which is even mentioned in the official Redux docs, would be that important because I would rarely write that expensive map state functions for Redux connect() .
  • A new function is created with a new identity.
  • Pure render optimized React components can be extremely performant but it requires users to treat their data as immutable for it to work properly.

Pure render optimized React components can be extremely performant but it requires users to treat their data as immutable for it to work…
Continue reading “React.js pure render performance anti-pattern – Medium”

Why The Hipsters Recompose Everything – JavaScript Inside – Medium

Why the hipsters recompose everything:  #ReactJS

  • It’s important to note that these functions are catered towards function components but should work for class components none the less.
  • High order components are functions that expect a component and return a new component.
  • After creating the factory we return a new function which applies the mapping function with the passed in props.
  • mapProps expects a mapping function which returns a new function that itself awaits a component.
  • const enhance = mapProps(props => omit ([‘foo’] , props))

Building a Utility Library for React
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Higher Order Components: A React Application Design Pattern

Higher order components: A #ReactJS app design pattern

  • Because higher order components often wrap an existing component you’ll often find you can define them as a functional component.
  • You need some of your React components to be able to access this information, but rather than blindly making it accessible for every component you want to be more strict about which components receive the information.
  • We’ll discuss how pure functions keep code clean and how these same principles can be applied to React components.
  • In the React ecosystem these components are known as higher order components because they take an existing component and manipulate it slightly without changing the existing component .
  • A higher order function is a function that when called, returns another function.

Read the full article, click here.


@ReactiveConf: “Higher order components: A #ReactJS app design pattern”


Jack Franklin takes a look at Higher Order Components, a design pattern that helps keep your React applications tidy, well structured and easy to maintain.


Higher Order Components: A React Application Design Pattern

Thinking in React

Thinking in @reactjs with a bunch of @jsfiddle examples –

  • Use the props to filter the rows in ProductTable and set the values of the form fields in SearchBar .
  • Step 1: Break the UI into a component hierarchy #
  • Find a common owner component (a single component above all the components that need the state in the hierarchy).
  • If you’re familiar with the concept of state , don’t use state at all to build this static version.
  • If you can’t find a component where it makes sense to own the state, create a new component simply for holding the state and add it somewhere in the hierarchy above the common owner component.

Read the full article, click here.


@oskar: “Thinking in @reactjs with a bunch of @jsfiddle examples –”


React is, in my opinion, the premier way to build big, fast Web apps with JavaScript. It has scaled very well for us at Facebook and Instagram.


Thinking in React