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next.js/lib/router/router.js
George Pantazis 085b2f806a Add Router method to execute custom logic before popstate events (#3956)
* Add router method to inject code before popstate events

* Default _beforePopState, return true

* Fix link in README

* Re-order `if` statements per feedback
2018-03-31 16:21:51 +02:00

393 lines
11 KiB
JavaScript

/* global __NEXT_DATA__ */
import { parse, format } from 'url'
import EventEmitter from '../EventEmitter'
import shallowEquals from '../shallow-equals'
import PQueue from '../p-queue'
import { loadGetInitialProps, getURL, warn, execOnce } from '../utils'
import { _rewriteUrlForNextExport } from './'
const historyUnavailableWarning = execOnce(() => {
warn(`Warning: window.history is not available.`)
})
const historyMethodWarning = execOnce((method) => {
warn(`Warning: window.history.${method} is not available`)
})
export default class Router {
constructor (pathname, query, as, { pageLoader, Component, ErrorComponent, err } = {}) {
// represents the current component key
this.route = toRoute(pathname)
// set up the component cache (by route keys)
this.components = {}
// We should not keep the cache, if there's an error
// Otherwise, this cause issues when when going back and
// come again to the errored page.
if (Component !== ErrorComponent) {
this.components[this.route] = { Component, err }
}
// Handling Router Events
this.events = new EventEmitter()
this.pageLoader = pageLoader
this.prefetchQueue = new PQueue({ concurrency: 2 })
this.ErrorComponent = ErrorComponent
this.pathname = pathname
this.query = query
this.asPath = as
this.subscriptions = new Set()
this.componentLoadCancel = null
this.onPopState = this.onPopState.bind(this)
this._beforePopState = () => true
if (typeof window !== 'undefined') {
// in order for `e.state` to work on the `onpopstate` event
// we have to register the initial route upon initialization
this.changeState('replaceState', format({ pathname, query }), getURL())
window.addEventListener('popstate', this.onPopState)
}
}
async onPopState (e) {
if (!e.state) {
// We get state as undefined for two reasons.
// 1. With older safari (< 8) and older chrome (< 34)
// 2. When the URL changed with #
//
// In the both cases, we don't need to proceed and change the route.
// (as it's already changed)
// But we can simply replace the state with the new changes.
// Actually, for (1) we don't need to nothing. But it's hard to detect that event.
// So, doing the following for (1) does no harm.
const { pathname, query } = this
this.changeState('replaceState', format({ pathname, query }), getURL())
return
}
// If the downstream application returns falsy, return.
// They will then be responsible for handling the event.
if (!this._beforePopState(e.state)) {
return
}
const { url, as, options } = e.state
this.replace(url, as, options)
}
update (route, Component) {
const data = this.components[route]
if (!data) {
throw new Error(`Cannot update unavailable route: ${route}`)
}
const newData = { ...data, Component }
this.components[route] = newData
if (route === this.route) {
this.notify(newData)
}
}
async reload (route) {
delete this.components[route]
this.pageLoader.clearCache(route)
if (route !== this.route) return
const { pathname, query } = this
const url = window.location.href
this.events.emit('routeChangeStart', url)
const routeInfo = await this.getRouteInfo(route, pathname, query, url)
const { error } = routeInfo
if (error && error.cancelled) {
return
}
this.notify(routeInfo)
if (error) {
this.events.emit('routeChangeError', error, url)
throw error
}
this.events.emit('routeChangeComplete', url)
}
back () {
window.history.back()
}
push (url, as = url, options = {}) {
return this.change('pushState', url, as, options)
}
replace (url, as = url, options = {}) {
return this.change('replaceState', url, as, options)
}
async change (method, _url, _as, options) {
// If url and as provided as an object representation,
// we'll format them into the string version here.
const url = typeof _url === 'object' ? format(_url) : _url
let as = typeof _as === 'object' ? format(_as) : _as
// Add the ending slash to the paths. So, we can serve the
// "<page>/index.html" directly for the SSR page.
if (__NEXT_DATA__.nextExport) {
as = _rewriteUrlForNextExport(as)
}
this.abortComponentLoad(as)
// If the url change is only related to a hash change
// We should not proceed. We should only change the state.
if (this.onlyAHashChange(as)) {
this.changeState(method, url, as)
this.scrollToHash(as)
return true
}
const { pathname, query } = parse(url, true)
// If asked to change the current URL we should reload the current page
// (not location.reload() but reload getInitalProps and other Next.js stuffs)
// We also need to set the method = replaceState always
// as this should not go into the history (That's how browsers work)
if (!this.urlIsNew(pathname, query)) {
method = 'replaceState'
}
const route = toRoute(pathname)
const { shallow = false } = options
let routeInfo = null
this.events.emit('routeChangeStart', as)
// If shallow === false and other conditions met, we reuse the
// existing routeInfo for this route.
// Because of this, getInitialProps would not run.
if (shallow && this.isShallowRoutingPossible(route)) {
routeInfo = this.components[route]
} else {
routeInfo = await this.getRouteInfo(route, pathname, query, as)
}
const { error } = routeInfo
if (error && error.cancelled) {
return false
}
this.events.emit('beforeHistoryChange', as)
this.changeState(method, url, as, options)
const hash = window.location.hash.substring(1)
this.set(route, pathname, query, as, { ...routeInfo, hash })
if (error) {
this.events.emit('routeChangeError', error, as)
throw error
}
this.events.emit('routeChangeComplete', as)
return true
}
changeState (method, url, as, options = {}) {
if (typeof window.history === 'undefined') {
historyUnavailableWarning()
return
}
if (typeof window.history[method] === 'undefined') {
historyMethodWarning(method)
return
}
if (method !== 'pushState' || getURL() !== as) {
window.history[method]({ url, as, options }, null, as)
}
}
async getRouteInfo (route, pathname, query, as) {
let routeInfo = null
try {
routeInfo = this.components[route]
if (!routeInfo) {
routeInfo = { Component: await this.fetchComponent(route, as) }
}
const { Component } = routeInfo
if (typeof Component !== 'function') {
throw new Error(`The default export is not a React Component in page: "${pathname}"`)
}
const ctx = { pathname, query, asPath: as }
routeInfo.props = await this.getInitialProps(Component, ctx)
this.components[route] = routeInfo
} catch (err) {
if (err.code === 'PAGE_LOAD_ERROR') {
// If we can't load the page it could be one of following reasons
// 1. Page doesn't exists
// 2. Page does exist in a different zone
// 3. Internal error while loading the page
// So, doing a hard reload is the proper way to deal with this.
window.location.href = as
// Changing the URL doesn't block executing the current code path.
// So, we need to mark it as a cancelled error and stop the routing logic.
err.cancelled = true
return { error: err }
}
if (err.cancelled) {
return { error: err }
}
const Component = this.ErrorComponent
routeInfo = { Component, err }
const ctx = { err, pathname, query }
routeInfo.props = await this.getInitialProps(Component, ctx)
routeInfo.error = err
}
return routeInfo
}
set (route, pathname, query, as, data) {
this.route = route
this.pathname = pathname
this.query = query
this.asPath = as
this.notify(data)
}
beforePopState (cb) {
this._beforePopState = cb
}
onlyAHashChange (as) {
if (!this.asPath) return false
const [ oldUrlNoHash, oldHash ] = this.asPath.split('#')
const [ newUrlNoHash, newHash ] = as.split('#')
// If the urls are change, there's more than a hash change
if (oldUrlNoHash !== newUrlNoHash) {
return false
}
// If the hash has changed, then it's a hash only change.
// This check is necessary to handle both the enter and
// leave hash === '' cases. The identity case falls through
// and is treated as a next reload.
return oldHash !== newHash
}
scrollToHash (as) {
const [ , hash ] = as.split('#')
const el = document.getElementById(hash)
if (el) {
el.scrollIntoView()
}
}
urlIsNew (pathname, query) {
return this.pathname !== pathname || !shallowEquals(query, this.query)
}
isShallowRoutingPossible (route) {
return (
// If there's cached routeInfo for the route.
Boolean(this.components[route]) &&
// If the route is already rendered on the screen.
this.route === route
)
}
async prefetch (url) {
// We don't add support for prefetch in the development mode.
// If we do that, our on-demand-entries optimization won't performs better
if (process.env.NODE_ENV === 'development') return
const { pathname } = parse(url)
const route = toRoute(pathname)
return this.prefetchQueue.add(() => this.fetchRoute(route))
}
async fetchComponent (route, as) {
let cancelled = false
const cancel = this.componentLoadCancel = function () {
cancelled = true
}
const Component = await this.fetchRoute(route)
if (cancelled) {
const error = new Error(`Abort fetching component for route: "${route}"`)
error.cancelled = true
throw error
}
if (cancel === this.componentLoadCancel) {
this.componentLoadCancel = null
}
return Component
}
async getInitialProps (Component, ctx) {
let cancelled = false
const cancel = () => { cancelled = true }
this.componentLoadCancel = cancel
const props = await loadGetInitialProps(Component, ctx)
if (cancel === this.componentLoadCancel) {
this.componentLoadCancel = null
}
if (cancelled) {
const err = new Error('Loading initial props cancelled')
err.cancelled = true
throw err
}
return props
}
async fetchRoute (route) {
return this.pageLoader.loadPage(route)
}
abortComponentLoad (as) {
if (this.componentLoadCancel) {
this.events.emit('routeChangeError', new Error('Route Cancelled'), as)
this.componentLoadCancel()
this.componentLoadCancel = null
}
}
notify (data) {
this.subscriptions.forEach((fn) => fn(data))
}
subscribe (fn) {
this.subscriptions.add(fn)
return () => this.subscriptions.delete(fn)
}
}
function toRoute (path) {
return path.replace(/\/$/, '') || '/'
}