Restore Scroll

Restore the scroll positions of window and scrollable elements when the user navigates around a React Router app.

Temporarily a Plugin

Plan is to put this into React Router directly, but for now you can plug it in and help us get the bugs out (and write some tests, there aren't any yet!)

Usage

import React from 'react'
import { render } from 'react-dom'
import { Router, browserHistory, applyRouterMiddleware } from 'react-router'
import routes from './routes'

import {
  useHistoryRestoreScroll,
  useRouterRestoreScroll
} from 'react-router-restore-scroll'

// first enhance a history
const createHistory = useHistoryRestoreScroll(() => browserHistory)

// next create some router middleware
const routerRender = applyRouterMiddleware(
  useRouterRestoreScroll()
)

// then plug them into Router
render(
  <Router
    history={createHistory()}
    render={routerRender}
    routes={routes}
  />,
  document.getElementById('app')
)

Now the window's scroll positions will be automatically restored as you navigate around in a React Router app, and even when you navigate out of and back into it from external sites.

Restores Scrollable Elements Too

If you’ve got scrollable elements (overflow: auto|scroll) they can also be restored with the RestoreScroll component.

import { RestoreScroll } from 'react-router-restore-scroll'

// then in a component's render method, wrap your scrollable element
// in a `RestoreScroll` component. It needs a `scrollKey`.
<RestoreScroll scrollKey="one">
  <div style={{ height: '200px', overflow: 'auto', border: '1px solid' }}>
    <div style={{ height: '100px', background: 'hsl(0, 50%, 90%)' }}>scroll me</div>
    <div style={{ height: '100px', background: 'hsl(100, 50%, 90%)' }}>two</div>
    <div style={{ height: '100px', background: 'hsl(200, 50%, 90%)' }}>three</div>
  </div>
</RestoreScroll>

Non-React usage

The useHistoryRestoreScroll enhancer gives you a history with a restoreScroll property with three methods that you can use to integrate into any view layer that uses history (cycle.js, etc.).

import createBrowserHistory from 'history/lib/createBrowserHistory'
import useHistoryRestoreScroll from 'react-router-restore-scroll/lib/useHistoryRestoreScroll'

const history = useHistoryRestoreScroll(createBrowserHistory)()

// call this when a scrollable element is inserted into the dom, where
// `scrollKey` is a globally unique identifier for the node
history.restoreScroll.registerScroller(scrollKey, domNode)

// call this when it's removed from the dom
history.restoreScroll.unregisterScroller(scrollKey)

// call this
// - when the app first renders
// - after the app re-renders after a location change
history.restoreScroll.restoreWindow()

You can look at modules/RestoreWindowScroll.js and modules/RestoreScroll.js to see at which points in a React app these methods are all called.

We'll pull useHistoryRestoreScroll out into it's own package on npm eventually so that this use-case isn't required to bring in stuff that depends on React and React Router.

Difference from taion/scroll-behavior

• It ties into the router middleware to decide when to restore scroll positions so we don't need workarounds for async routes
• It restores scroll position of individual elements in addition to the window.
• It doesn't rely on location.key in preparation for history 3.0
• It does not have shouldUpdateScroll, but once route is on context we'll be able to implement the old ignoreScroll route prop or maybe a function like shouldUpdateScroll instead.