React Deco

React Deco Give back to JSX what is JSX’s

• Overview
• Installation
• Usage
• Components
  • If
  • Switch/When
  • Map
  • Bare
  • Await

Overview

React Deco is a library that aims to make React complex views more declarative, idiomatic, easy to read, and easy to write, by consequence more mantainables.

This library takes advantage of Render-Props pattern (effectively used by React Router and Downshift) to make possible to write conditionals and loops in a more declarative way while reducing visual cluttering.

Lets write a simple table of products with two columns Name and In Stock. If In Stock is 0 then a message Out of Stock should be displayed. Currently we should write something like the following:

function ProductTable({products}) {
  return (
    <table>
      <thead>
        <tr>
          <th>Name</th>
          <th>In Stock</th>
        </tr>
      </thead>
      {renderTableBody(products)}
    </table>
  )
}

function renderTableBody(products) {
  return (
    <tbody>
    {products.map((product) =>
      <tr>
        <td>{product.name}</td>
        {(product.inStock > 0)
          ? <td>{product.inStock}</td>
          : <td>Out of Stock</td>
        }
      </tr>
    )}
    </tbody>
  )
}

This library will turn the above code into:

function ProductTable({products}) {
  return (
    <table>
      <thead>
        <tr>
          <th>Name</th>
          <th>In Stock</th>
        </tr>
      </thead>
      <tbody>
      <Map target={products} with={(product) =>
        <tr>
          <td>{product.name}</td>
          <If test={product.inStock > 0}
            then={<td>{product.inStock}</td>}
            else={<td>Out of Stock</td>}
          />
        </tr>
      }/>
      </tbody>
    </table>
  )
}

Installation

// with yarn
yarn add react-deco

// with npm
npm install react-deco

Usage

// ES2015+ and TS
import {If, Map, Bare} from 'react-deco'

// CommonJS
var ReactDeco = require('react-deco')
var If = ReactDeco.If
var Map = ReactDeco.Map
var Bare = ReactDeco.Bare

Components

React-Deco exports some primitives wich holds reusable logic, to help developers to write presentational logic in JSX.

If

Conditionally render components based on the truthy-ness of evaluating the test prop. Render then if test evaluates to truthy, render else otherwise.

<If
  test={a > b}
  then={'a is greater then b'}
  else={'a is not greater than b'}
/>

Passign functions in then and else makes the rendering process more efficient because only one of both branches is evalueted depending on truthy-ness of test. See Short Circuit Evaluation

<If
  test={a > b}
  then={() => 'a is greater then b'}
  else={() => 'a is not greater than b'}
/>

Switch/When

Render the first When child whosetest prop evaluates to true.

<Switch>
  <When test={a > 1} render={() => <div> Foo </div>} />
  <When test={true} render={() => <div> Default </div>} />
</Switch>

Map

Render the result of dispatching to the map method of target passing the with function as the first argument.

<Map target={[1, 2, 3]} with={(item) =>
  <div key={item}>{item}</div>
} />

Bare

React Hooks addresses the same problem that this component was created for.

A component that its constructor, shouldComponentUpdate, and lifecycle methods can be assigned via props

<Bare shouldUpdate={shouldUpdateFn} render={() =>
  ...
} />

Bare componets accept the following props:

• render: render(self)
• constructor: constructor(self, props, ctx)
• didCatch: didCatch(self)
• didMount: didMount(self)
• didUpdate: didUpdate(self, prevState)
• shouldUpdate: shouldUpdate(self, nextState)
• willUnmount: willUnmount(self)

Additionaly, Bare components accepts a prop named pureBy. In case this property is provided the passed value will be used to compute the component purity using shallow comparison, if it is an array the shallow comparison will be computed by shallow-comparing each value in the array.

<Bare pureBy={client} render={() =>
  <div>{client.name}</div>
  <div>{client.age}</div>
} />

The above code will re-render only if one of the properties of the client object is different.

Bare components also contains a self reference called self, frequently useful to keep a reference to the component while destructuring in lifecycle params, example:

<Bare pureBy={client} didMount={({setState, self, state}) =>
  // use self
} />

setState can be used inside the constructor

Await

Render components based on the state of a promise. Renders then prop when the promise is resolved. Renders catch prop when the promise is rejected. Renders placeholder while the promise is not resolved nor rejected.

const usersPromise = fetch('users')
<Await promise={usersPromise} then={users =>
  ...
} />

Await componets accept the following props:

• promise
• then
• catch
• placeholder

Published under MIT Licence

(c) Yosbel Marin 2018