README.md

Get Screen Size Hook

This hook will use the breakpoints defined in @drawbotics/drylus-style-vars to identify screen size where the app is running.

Installation

$ npm install @drawbotics/use-screen-size @drawbotics/drylus-style-vars

Usage

import { useScreenSize } from '@drawbotics/use-screen-size';


const App = ({ children }) => {
  const { screenSize, ScreenSizes } = useScreenSize();
  return (
    <Page>
      {do {
        if (screenSize >= ScreenSizes.M) {
          <Header />
        }
      }}
      {do {
        if (screenSize < ScreenSizes.S) {
          <Sidebar />
        }
      }}
      <Content>
        {children}
      </Content>
    </Page>
  )
};


export default App;

Api

The hook returns two properties screenSize and ScreenSizes:

• screenSize is equivalent to the current size of the screen following the current media query matching the size
• ScreenSizes is a constant with the screen size value matching its size definition:

const ScreenSizes = {
  XS: 1,
  S: 2,
  M: 3,
  L: 4,
  XL: 5,
};

This allows you to mimic the CSS way of writing queries, but in a more verbose way in JavaScript. You can use the comparative operators <,=,> to determine what should be rendered on the screen.

If you want to render something when the screen is smaller or equal to a small size:

  if (screenSize <= ScreenSizes.S) {
    // Content for small screens and lower
  }
  else {
    // Content for screens larger than small
  }

You can also target specific sizes with the === operator:

  if (screenSize === ScreenSizes.L) {
    // Only render this content when the screen is L (smaller than XL and larger than S)
  }

For anything larger than XL you should use the following condition:

  if (screnSize > ScreenSizes.XL) {
    // Content for big screens
  }

Order of conditions

As with CSS @media queries, you have to check the screen size in the same order, i.e. from largest to smallest, otherwise the first one will always apply. This is because a small screen still falls within a large one, but not vice versa.

---

There's also another utility function called getScreenSize that returns exactly the contents of the value returned by the hook (properties of screenSize) (it's actually used internally in the hook) but that won't update the value based on the resize events.

Example:

import { getScreenSize } from '@drawbotics/use-screen-size';

console.log(getScreenSize());

// on medium screen prints
3