Understanding higher-order components

  • Why use HOC: Promote reuse of logic across React components.
  • How to use HOC: The core structure of a HOC is a function that takes a component and returns a new component.
  • HOC are pure functions with no side-effects because the component passed in, is wrapped in a new component.
  • The HOC looks like this: – – State now has a property to inject data from the API fetch into the wrapped component via the prop.
  • React Redux connect has a different function signature of a function returning a function which accepts one argument (ie, ‘component’) to create a HOC.

Understand why and how to use higher-order components with React JS

Continue reading “Understanding higher-order components”

Using RxJS with React.js: Part 3 — Dispatching events from Component

  • (Check out FrintJS on GitHub for more documentation on combining the power of RxJS with React)Illustration of unidirectional flow between Subject and ComponentUnidirectional cycleEarlier we saw an example of HoC streaming props to the base component.
  • Let’s now look at ways how we can dispatch events from inside the base component, update some value, and the updated value will then be streamed back to the component completing one unidirectional cycle.We can take the example of a form input field.
  • To keep things simple, let’s say BehaviorSubject is a kind of Subject, that can already start with an initial value.import { BehaviorSubject } from ‘rxjs’;const subject$ = new = console.log(x)); // prints `foo` right awayThe base Component with form inputLet’s say this is our base component:import React from ‘react’const MyComponent =…
  • First one is a stream of the input value, and the latter for handling the change.import { BehaviorSubject, Observable } from ‘rxjs’;const formInput$ = new BehaviorSubject(‘foo’); // with initial valueconst handlers$ = Observable.of({ handleChange: value = formInput$.
  • scan(function (props, emitted) { return { …props, …emitted }; });Observing the base ComponentNow that we have the props$ observable ready, we can integrate it with our base complement easily using the observe function from FrintJS:import { observe } from ‘frint-react’;const ObservedRoot = observe(function () { return props$;})(MyComponent);Now you can stream…

Earlier we saw an example of HoC streaming props to the base component. Let’s now look at ways how we can dispatch events from inside the base component, update some value, and the updated value will…
Continue reading “Using RxJS with React.js: Part 3 — Dispatching events from Component”

Deep dive into observed Components with React.js and FrintJS

  • Higher-order componentThe API of the observe higher-order component (HoC) is quite simple:import React from ‘react’;import { observe } from ‘frint-react’;function MyComponent(props) { return div…/div;}const ObservedComponent = default ObservedComponent;It receives a function (that we called fn above), where you can generate your props that will be ultimately passed to your target…
  • Generating props synchronouslyThe fn function also gives you access to the FrintJS App’s instance:const ObservedComponent = observe(function (app) { // this will be the `props` in MyComponent return {}; })(MyComponent);Since you have access to your app instance, you can also get values from it, including providers:const ObservedComponent = observe(function (app)…
  • Because they have this dynamic nature, the observe HoC gives you access to parent props as an Observable:const ObservedComponent = observe(function (app, props$) { // …})(MyComponent);In addition to your FrintJS App instance (app), there is a second argument props$, which is props passed down to you from the parent Component…
  • But as your application grows, there will be times, when you need to work with multiple Observables and return a single props stream.This is where a helper function called streamProps shipped with frint-react can come handy.If you are an RxJS ninja, you may skip this part =DThe streamProps function will…
  • In that case, you may want to pass some default props to your target component before new values are generated.The streamProps helper function receives an optional first argument, where you can pass your default props:import { streamProps } from ‘frint-react’;const defaultProps = { foo: ‘n/a’, bar: ‘n/a’, baz: ‘n/a’,};const props$…

Our focus in this article will be about using the observe higher-order component, shipped from frint-react package. To make the most out of this, it is advised that you read these previous articles…
Continue reading “Deep dive into observed Components with React.js and FrintJS”

React Higher-Order Components in TypeScript made simple

  • These attributes were chosen to illustrate all the aspects of HOCs while keeping the HOC as simple as possible.PropsThere are three types of props we need to consider when creating a HOC: OriginalProps, ExternalProps and InjectedProps.OriginalProps are props of the wrapped component.
  • The state of the HOC is simple, just the count of the clicksOptionsAs stated before, HOC is a function that takes a component and returns a component.While this is true, many HOCs take the form of curried HOC factories (like the mentioned connect from react-redux) that take a configuration object…
  • If you need to interact with props or states from here, the only way to do it is to specify options as functions, that take the props or states as arguments.For ClickCounted the options are simple – a flag indicating whether to console.log on click:Putting it all togetherHaving declared all the…
  • Now that we have the signature, all that’s left is to implement the HOC:First, we define the type alias for the resulting component’s props — the TOriginalProps ExternalProps to simplify its reuse.
  • Props and state are passed to it with whatever was in the OriginalProps along with the clickCount from the HOC state.Using the HOCTo illustrate how to use our HOC, we create a Demo component, that displays a different text depending on the amount of clicks and a custom message.Notice the type…

On a simple React Higher-Order Component, the process of writing them in TypeScript is demonstrated along with advice and rationals behind the type declarations
Continue reading “React Higher-Order Components in TypeScript made simple”

Using RxJS with React.js: Part 3 — Dispatching events from Component

Using RxJS with React.js: Part 3 - Dispatching events from Component

  • Using RxJS with React.js: Part 3 — Dispatching events from ComponentThis is the third part of the series.Illustration of unidirectional flow between Subject and ComponentUnidirectional cycleEarlier we saw an example of HoC streaming props to the base component.
  • Let’s now look at ways how we can dispatch events from inside the base component, update some value, and the updated value will then be streamed back to the component completing one unidirectional cycle.We can take the example of a form input field.
  • To keep things simple, let’s say BehaviorSubject is a kind of Subject, that can already start with an initial value.import { BehaviorSubject } from ‘rxjs’;const subject$ = new = console.log(x)); // prints `foo` right awayThe base Component with form inputLet’s say this is our base component:import React from ‘react’const MyComponent = React.createClass({ render() { const { value, handleChange } = this.props; return ( div input type=”text” value={value} onChange={e = handleChange(e.target.value)} / pCurrent value: {value}/p /div ); }});From the base component, we are accessing the props value and handleChange.
  • First one is a stream of the input value, and the latter for handling the change.import { BehaviorSubject, Observable } from ‘rxjs’;const formInput$ = new BehaviorSubject(‘foo’); // with initial valueconst handlers$ = Observable.of({ handleChange: value = formInput$.
  • scan(function (props, emitted) { return { …props, …emitted }; });Observing the base ComponentNow that we have the props$ observable ready, we can integrate it with our base complement easily using the observe function from FrintJS:import { observe } from ‘frint-react’;const ObservedRoot = observe(function () { return props$;})(MyComponent);Now you can stream the props, including both the input value and the change handler from your HoC, and also trigger changes in the Subject from your Component’s events.Live demoVisit this example in JSBin.

Earlier we saw an example of HoC streaming props to the base component. Let’s now look at ways how we can dispatch events from inside the base component, update some value, and the updated value will…
Continue reading “Using RxJS with React.js: Part 3 — Dispatching events from Component”

Using Higher Order Components in a React Application

  • If you have started using ReactJS recently often you might have felt that you are performing repeated logic in many components.
  • Well Higher Order Component (HOC) provides solution to such a kind of problems.
  • A function (Functional component in React) which takes a component and gives back another component.
  • So the exact benefits are:

    Functional components started from React V15.

  • But apart from that if we are careful enough we can have an architecture which can abstract logic that can be shared across other presentational components using HOC has great benefits.

If you have started using ReactJS recently often you might have felt that you are performing repeated logic in many components. For example consider an app having:
Continue reading “Using Higher Order Components in a React Application”

React Higher Order Components in depth — Medium

  • Props Proxy: The HOC manipulates the props being passed to the WrappedComponent W ,
  • We also pass through the props that the HOC receives the name Props Proxy .
  • Parent Components are just React Components that have some children.
  • A Higher Order Component is just a React Component that wraps another one.
  • Parent Components can be used freely in an Elements tree, they are not restricted to once per Component class as HOCs are.

Read the full article, click here.


@dan_abramov: “Deep writeup by @franleplant on higher order components in @reactjs”


AbstractThis post is targeted to advanced users that want to exploit the HOC pattern. If you are new to React you should probably start by reading React’s …


React Higher Order Components in depth — Medium