Using Props in React – ziv zamechek – Medium

Using Props in React  #javascript #react #reactjs

  • In between the time it takes the first render of the component to fetching this data and setting it on our state that takes some time and during that time the length of videos is equal to 0 that is the reason that we see 0 for half a second when refreshing the page.
  • this.state = { videos: [] };When it is first rendered it does search of surfboards and it gets the response from this.stateApp is the parent of video list and video list need to get access to the videos that are in the app state.
  • passing data from the parent component App to the child component VideoList we are passing the list of videos just by defining a property on the JSX tag.Here we are passing video list to render method.
  • Anytime when App re render VideoList will get the videos as well.So now we have a functional VideoList component and it has array of videos to render.
  • Our video list component will receive props that contain an array of videos so we just loop over this array and for each video will generate one instance of video list for each item.Now each VideoListItem which is intended to show a single video now it will show a single li with a video.A map is a built in method that is a property of an array.

When we use functional component the props object will arrive as an argument to the function. const videos = props.videos; this is the array of videos. {props.videos.length} so this is saying that…
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redux mapStateToProps optimization – Cvetanov Goce – Medium

redux mapStateToProps optimization  #redux #react #javascript #reactjs

  • mapStateToProps can now return a function instead of an object.Note: in advanced scenarios where you need more control over the rendering performance, mapStateToProps() can also return a function.
  • In this case, that function will be used as mapStateToProps() for a particular component instance.
  • [from the official docs]If redux receives an implementation which returns a function it performs a closure for wrapping the own props of the component and therefore bypasses the invocation of the mapStateToProps every time the component changes it’s props received from the parent component.
  • How this is done can be seen here.We can now rework our implementation of the MyBlogs component in the following way and achieve a minor performance boost.function ownProps) { // a closure for ownProps is created // this factory is not invoked everytime the component // changes it’s props return function mapStateToProps(state) { return { blogs: state.blogs.filter(blog = blog.author === ownProps.user) }; };}export default using the component’s own props inside mapStateToProps, wrap the mapStateToProps function with a mapStateToPropsFactory which will return the function itself instead of the object directly and redux will not invoke your mapStateToPropsFactory for every parent prop changes.Thanks to my mentor Oliver Lazoroski for pointing this out to me and I will share his TL;DR; remark on this:Think of it like this, if redux receives a mapStateToProps which has ownProps as second argument and it returns an object, it switches off every optimization it makes for your connected component.This was my first of many articles on medium and I hope you will find it useful.

Redux is an open source implementation (aren’t they all?) of the flux architecture suggested by Facebook as a compliant standard for working with data in large React applications. Created by Dan…
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Redux, Immutability, and Higher Order Components

Redux, immutability, and higher order components:  #ReactJS

  • A higher order component is exactly what it sounds like — it is the React component equivalent of a higher order function.
  • In React, a higher order component is a function that accepts a component and returns an enhanced component with superhero abilities.
  • A simple example of a higher order function in Haskell that takes a function and applies it twice to something.
  • , connect() is, through mapDispatchToProps() , subscribing the TodoList component to a change handler that will toggle a todo when the todo is clicked.
  • Well, arguably, one of the key concepts when using Redux with React lies in a higher order component: connect() .

Read the full article, click here.


@ReactiveConf: “Redux, immutability, and higher order components: #ReactJS”


As I wrote in a previous blog post, immutability is an important concept that can bring many benefits to development. In fact, it’s been embraced by javascript land, most notably by the ultra-popular framework, Redux.


Redux, Immutability, and Higher Order Components