Declarative D3 transitions with React 16.3

  • The new React 16.3 brings some changes to the ecosystem that change how we go about integrating React and D3 to build data visualizations.
  • Because the re-render is instant, you don’t have time to show a nice transition going into the new state.
  • We use to give D3 control of the DOM node, run a transition that lasts milliseconds, define an easing function, and change the attribute to the new value we got from props.
  • When that value changes, the transitions itself to its new position.
  • If we flip positions during a transition, D3 is smart enough to stop the previous transition and start a new one.

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Writing Easily Testable Code with Stateless Components in React.js

Writing Easily Testable Code with Stateless Components in #React.JS  #javascript #testing

  • By relying on pure components, developers end up writing reusable code that’s extremely easy to test, which leads to better application architecture.
  • Personally, I like the term “pure component” because it’s indicative of what the code really is — a pure function sprinkled with some JSX.
  • In addition to these benefits, pure components also make it extremely easy to test code with any crazy props that you wish.
  • Like a pure function, pure components will always map the same input to the same output, therefore, if we can think of the scenario, we can test how our component will react.
  • As we just saw, the code for functional components provides us awesome intel for everything we need to know in order to write effective tests.

Functional Stateless Components provides clean syntax that allows us to
write more declarative code. We will look at stateless components and finish up with some unit tests in this article.
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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…
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Writing Easily Testable Code with Stateless Components in React.js

Writing Easily Testable Code with Stateless Components in #React.JS  #javascript #testing

  • The use of Stateless Functional Components (a.k.a. “pure” or “dumb” components) in React.js continues to grow since first it was released in React 0.14, and for good reasons.
  • By relying on pure components, developers end up writing reusable code that’s extremely easy to test, which leads to better application architecture.
  • Personally, I like the term “pure component” because it’s indicative of what the code really is — a pure function sprinkled with some JSX.
  • In addition to these benefits, pure components also make it extremely easy to test code with any crazy props that you wish.
  • As we just saw, the code for functional components provides us awesome intel for everything we need to know in order to write effective tests.

Functional Stateless Components provides clean syntax that allows us to write more declarative code. We will look at stateless components and finish up with some unit tests in this article.
Continue reading “Writing Easily Testable Code with Stateless Components in React.js”

Writing Easily Testable Code with Stateless Components in React.js

  • The use of Stateless Functional Components (a.k.a. “pure” or “dumb” components) in React.js continues to grow since first it was released in React 0.14, and for good reasons.
  • By relying on pure components, developers end up writing reusable code that’s extremely easy to test, which leads to better application architecture.
  • Personally, I like the term “pure component” because it’s indicative of what the code really is — a pure function sprinkled with some JSX.
  • In addition to these benefits, pure components also make it extremely easy to test code with any crazy props that you wish.
  • As we just saw, the code for functional components provides us awesome intel for everything we need to know in order to write effective tests.

Functional Stateless Components provides clean syntax that allows us to write more declarative code. We will look at stateless components and finish up with some unit tests in this article.
Continue reading “Writing Easily Testable Code with Stateless Components in React.js”