redux-responsive


A redux reducer for managing the responsive state of your application.

Example

``js
// MyComponent.js

import React from 'react'
import {connect} from 'react-redux'

// grab only the responsive state from the store
// (assuming you have put the responsiveStateReducer under
// the key browser in your state tree)
function browserSelector({browser}) {
return {browser}
}

@connect(browserSelector)
class MyComponent extends React.Component {
render() {
// grab the responsive state off of props
const {browser} = this.props

let message = The viewport's current media type is: ${browser.mediaType}.

if (browser.lessThan.small) {
message += 'Secret message for viewports smaller than than the "small" breakpoint!'
} else if (browser.lessThan.medium) {
message += 'Secret message for viewports between the "small" and "medium" breakpoints!'
} else {
message += 'Message for viewports greater than the "medium" breakpoint.'
}

return (



{message}



)
}
}
`

Why Store Responsive State in Redux?

redux-responsive does not require that you use React as your view library. However, since that is what is commonly used alongside redux, this documentation employs common React patterns.

There are many solutions for cleanly handling responsive designs in React applications. One common approach is to wrap a component in another component which is responsible for handling the behavior and passing the information down as a prop. While this at first seems good and the "react way", as the behavior gets more complicated, this quickly leads to a lot of boilerplate code in a single component. Also, depending on the implementation, it is possible that many copies of the responsive wrapper would create many different resize handlers.

Using a specialized store not only reduces the overall noise in a component, but also guarantees that only a single event listener is listening for resize.

Setup

First, add the reducer to the root of your reducer tree (you can name it whatever you want).

`js
// reducer.js
import {combineReducers} from 'redux'
import {responsiveStateReducer} from 'redux-responsive'

export default combineReducers({
browser: responsiveStateReducer,
})
`

Second, you must add required event handlers to keep the responsive state up to date. redux-responsive uses
MediaQueryLists to efficiently update the
store only when required. To do this, use the provided store enhancer.

`js
// store.js

import {createStore} from 'redux'
import {responsiveStoreEnhancer} from 'redux-responsive'
import reducer from './reducer'

const store = createStore(reducer, responsiveStoreEnhancer)

// or, if you have an initial state for the store
const store = createStore(reducer, initialState, responsiveStoreEnhancer)

export default store
`

Note that if you are also using some middlewares, the call will look more like this:

`js
import {createStore, applyMiddleware, compose} from 'redux'
import {responsiveStoreEnhancer} from 'redux-responsive'
import reducer from './reducer'

const store = createStore(
reducer,
compose(
responsiveStoreEnhancer,
applyMiddleware(middleware1, middleware2)
)
)

// or, if you have an initial state for the store
const store = createStore(
reducer,
initialState,
compose(
responsiveStoreEnhancer,
applyMiddleware(middleware1, middleware2)
)
)

export default store
`

Now your store is ready to use. The store's default breakpoints match common device sizes and are accessible by the following names in your view:

`js
const defaultBreakpoints = {
extraSmall: 480,
small: 768,
medium: 992,
large: 1200,
}
`

The Responsive State

The responsiveStateReducer (and the reducer returned by createResponsiveStateReducer) adds an object with the following keys to the store:


- mediaType: (string) The largest breakpoint category that the browser satisfies.
- orientation: (string) The browser orientation. Has three possible values: "portrait", "landscape", or null.
- lessThan: (object) An object of booleans that indicate whether the browser is currently less than a particular breakpoint.
- greaterThan: (object) An object of booleans that indicate whether the browser is currently greater than a particular breakpoint.
- is: (object) An object of booleans that indicate whether the browser is current that particular breakpoint.

For example, if you put the responsive state under the key browser (as is done in the examples above) then you can access the browser's width and current media type, and determine if the browser is wider than the medium breakpoint like so

`js
// get the current state from the store
const state = store.getState()

// browser media type (e.g. "large")
state.browser.mediaType
// browser orientation (takes a null value on desktops)
state.browser.orientation
// true if browser width is greater than the "medium" breakpoint
state.browser.greaterThan.medium
// true if browser.mediaType === 'small'
state.browser.is.small
`




Using Custom Breakpoints

You can also create your own reducer based on custom breakpoints:

`js
// reducer.js

import {combineReducers} from 'redux'
import {createResponsiveStateReducer} from 'redux-responsive'

export default combineReducers({
browser: createResponsiveStateReducer({
extraSmall: 500,
small: 700,
medium: 1000,
large: 1280,
extraLarge: 1400,
}),
})
`

$3

When the browser is wider than the largest breakpoint, it's mediaType value is infinity. In order to
change this value, add the infinity field to the object pass as a second argument to createResponsiveStateReducer:

`es6
// reducer.js

import {combineReducers} from 'redux'
import {createResponsiveStateReducer} from 'redux-responsive'

export default combineReducers({
// passing null to the reducer factory uses the default breakpoints
browser: createResponsiveStateReducer(null, {
infinity: "veryBig"
})
})
`

Adding custom/computed fields to the responsive state

In some cases, you may want to add computed fields to the responsive state. For example,
an application may frequently need to know when the browser is greaterThanOrEqual to
a particular breakpoint. In order to support this, redux-responsive lets you pass a
function and to createResponsiveStateReducer arguments as the extraFields key.
This function will recieve an object with the responsive state and returns an object
with the new keys to be injected into the state whenever it is recalculated:

`es6
// reducer.js

import {combineReducers} from 'redux'
import {createResponsiveStateReducer} from 'redux-responsive'
import {transform} from 'lodash'

export default combineReducers({
browser: createResponsiveStateReducer(null, {
extraFields: ({ greaterThan, is }) => ({
// greaterThanOrEqual is built by transforming greaterThan
greaterThanOrEqual: transform(greaterThan, (result, value, mediaType) => {
// and combining the value with the is field
result[mediaType] = value || is[mediaType]
}, {})
}),
})
})
`

$3

In some cases, you may want to have a window attributes tracked in your responsive state (for example, width).
To accomplish this, the first step is to add the custom field as described above.

`es6
// reducer.js

import {combineReducers} from 'redux'
import {createResponsiveStateReducer} from 'redux-responsive'
import {transform} from 'lodash'

export default combineReducers({
browser: createResponsiveStateReducer(null, {
extraFields: () => ({
width: window.innerWidth
}),
})
})
`


When doing this, keep in mind that the responsive state enhancer only causes the
responsive state to be recalculated when the browser actually transitions between
states. It does not recalculate on every resize. Therefore, you might also need
to add an event handler that recalculates the state at another time:

`es6
// store.js

import {calculateResponsiveState} from 'redux-responsive'

const store = ...

window.addEventListener('resize', () => store.dispatch(calculateResponsiveState(window)))
`




Server-side Rendering

Isomorphic applications must make sure that the sever-rendered markup matches the
DOM rendered by the client. Setting the calculateInitialState option in the
createResponsiveStoreEnhancer factory method to false tells the reducer
to skip the initial responsive state calculation. The responsive state will
contain the default values on both the server and the client side.

`js
// store/configureStore.js

import {createStore} from 'redux'
import {createResponsiveStoreEnhancer} from 'redux-responsive'
import reducer from './reducer'

const store = createStore(
reducer,
createResponsiveStoreEnhancer({calculateInitialState: false}))

export default store
`

The application should explicitly dispatch the action to recalculate the responsive
state when the application is rendered by the client.


`jsx
// client.js

// external imports
import ReactDOM from 'react-dom'
import {calculateResponsiveState} from 'redux-responsive'
// local imports
import store from 'path/to/store'

// render the application
ReactDOM.render(

// ...
,
document.getElementById('app')
)

// calculate the initial state
store.dispatch(calculateResponsiveState(window))
`

$3

If you know the initial media type for your application (by doing something like looking at
the user-agent) you can set the initial media type with the initialMediaType key to the
reducer factory:

`es6
const reducer = createResponsiveStateReducer(null, {initialMediaType: 'small'})
`

Higher-Order Components

When building responsive applications in react, it's common to
implement styles for each breakpoint and then apply them like so:

`jsx
const commonStyle = {...}

const styles = {
element: {
...commonStyle,
color: 'blue',
},
elementThin: {
...commonStyle,
color: 'black',
}
}

// somewhere in your component...