felthy/react-sizes

:left_right_arrow: Hoc to easily map window sizes to props.

Install

yarn add react-sizes

npm install react-sizes

What and why

React Sizes is a high-order component with a high performance that transform window sizes (width and height) into props.
You can check inside your component, for example, if user's window is less than 480 pixels of width, and add a custom content.

It can be very powerful for when you need to display different content for mobile and desktop. But it's not limited to this case. Just use that at your needs.

Usage

With class component.

import React, { Component } from 'react';
import Sizes from 'react-sizes';

class MyComponent extends Component {
  render() {
    return (
      <div>{this.props.isMobile ? 'Is Mobile' : 'Is Not Mobile'}</div>
    );
  }
}

const mapSizesToProps = ({ width }) => ({
  isMobile: width < 480,
});

export Sizes(mapSizesToProps)(MyComponent);

You can play with this example here.

As decorator.

import React from 'react';
import Sizes from 'react-sizes';

@Sizes(({ width }) => ({ isMobile: width < 480 }))
class MyComponent extends Component {
  render() {
    return (
      <div>{this.props.isMobile ? 'Is Mobile' : 'Is Not Mobile'}</div>
    );
  }
}

export default MyComponent;

With functional component.

import React from 'react';
import Sizes from 'react-sizes';

const MyComponent = ({ isMobile }) => (
  <div>{isMobile ? 'Is Mobile' : 'Is Not Mobile'}</div>
);

const mapSizesToProps = ({ width }) => ({
  isMobile: width < 480,
});

export Sizes(mapSizesToProps)(MyComponent);

Interoperate with other libraries.

import React from 'react';
import Sizes from 'react-sizes';
import { withState, compose } from 'recompose';

const enhancer = compose(
  withState('counter', 'setCounter', 0),
  Sizes(({ width }) => ({ isMobile: width < 480 })),
);

const MyComponent = enhancer(({ isMobile, counter, setCounter }) => (
  <div>
    <div>
      Count: {counter} <button onClick={() => setCounter(n => n + 1)}>Increment</button>
    </div>
    <div>{isMobile ? 'Is Mobile' : 'Is Not Mobile'}</div>
  </div>
));

export default MyComponent;

With presets selectors.

- const mapSizesToProps = ({ width }) => ({
-   isMobile: width < 480,
- });

+ const mapSizesToProps = sizes => ({
+  isMobile: Sizes.isMobile(sizes),
+ });

Presets Selectors

You can check all our presets selectors at our main code src/Sizes.js.

Sizes.isMobile = ({ width }) => width < 480;
Sizes.isTablet = ({ width }) => width >= 480 && width < 1024;
Sizes.isDesktop = ({ width }) => width >= 1024;

Sizes.isGtMobile = (sizes) => !Sizes.isMobile(sizes);
Sizes.isGtTablet = (sizes) => Sizes.isDesktop(sizes);

Sizes.isStTablet = (sizes) => Sizes.isMobile(sizes);
Sizes.isStDesktop = (sizes) => !Sizes.isStDesktop(sizes);

Sizes.isTabletAndGreater = (sizes) => !Sizes.isMobile(sizes);
Sizes.isTabletAndSmaller = (sizes) => !Sizes.isStDesktop(sizes);

If it don't fit to your needs, you can create your own selectors.

// utils/sizes/selectors.js
export const isntDesktop = ({ width }) => width < 1024;
export const backgroundColor = ({ width }) => width < 480 ? 'red' : 'green';

// your component
import { isntDesktop, backgroundColor } from 'utils/sizes/selectors';

const mapSizesToProps = sizes => ({
  canDisplayMobileFeature: isntDesktop(sizes),
  backgroundColor: backgroundColor(sizes),
});

sizes argument is an object with width and height properties and represents DOM window width and height.

Performance Notes

Global listener

Window resize event listener is grouped at one global listener only. So you can have as many components as you want using Sizes hoc, which will not have multiple resize listeners, but only one that will dispatch for all instances.

Don't worry, Sizes handles componentWillUnmount to remove unnecessary callbacks. When each component unmounted, it unsubscribe for global dispatches, and when last component is unmounted, the listener is removed.

Throttle

By now the listener callback is hardcoded as throttle function of 200ms. Because of having a global listener, we have a limitation on changing this behavior. I don't see it as tradeoff, and I think it can have good workarounds. Then, for the future, I intend to work to bring a solution to this important customization.

Guide

mapSizesToProps(sizes)

sizes argument is an object with width and height of DOM window.

const mapSizesToProps = sizes => {
  console.log(sizes) // { width: 1200, height: 720 } (example)
};

In pratice, it is a callback that return props that will injected into your Component.

const mapSizesToProps = function(sizes) {
  const props = {
    backgroundColor: sizes.width < 700 ? 'red' : 'green',
  };

  return props;
};

But you can simplify this to stay practical and elegant.

const mapSizesToProps = ({ width }) => ({
  backgroundColor: width < 700 ? 'red' : 'green',
});

Contribute

You can help improving this project sending PRs and helping with issues.
Also you ping me at Twitter