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node_modules/vue-router/src/util/scroll.js

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+/* @flow */
+
+import type Router from '../index'
+import { assert } from './warn'
+import { getStateKey, setStateKey } from './state-key'
+import { extend } from './misc'
+
+const positionStore = Object.create(null)
+
+export function setupScroll () {
+  // Prevent browser scroll behavior on History popstate
+  if ('scrollRestoration' in window.history) {
+    window.history.scrollRestoration = 'manual'
+  }
+  // Fix for #1585 for Firefox
+  // Fix for #2195 Add optional third attribute to workaround a bug in safari https://bugs.webkit.org/show_bug.cgi?id=182678
+  // Fix for #2774 Support for apps loaded from Windows file shares not mapped to network drives: replaced location.origin with
+  // window.location.protocol + '//' + window.location.host
+  // location.host contains the port and location.hostname doesn't
+  const protocolAndPath = window.location.protocol + '//' + window.location.host
+  const absolutePath = window.location.href.replace(protocolAndPath, '')
+  // preserve existing history state as it could be overriden by the user
+  const stateCopy = extend({}, window.history.state)
+  stateCopy.key = getStateKey()
+  window.history.replaceState(stateCopy, '', absolutePath)
+  window.addEventListener('popstate', handlePopState)
+  return () => {
+    window.removeEventListener('popstate', handlePopState)
+  }
+}
+
+export function handleScroll (
+  router: Router,
+  to: Route,
+  from: Route,
+  isPop: boolean
+) {
+  if (!router.app) {
+    return
+  }
+
+  const behavior = router.options.scrollBehavior
+  if (!behavior) {
+    return
+  }
+
+  if (process.env.NODE_ENV !== 'production') {
+    assert(typeof behavior === 'function', `scrollBehavior must be a function`)
+  }
+
+  // wait until re-render finishes before scrolling
+  router.app.$nextTick(() => {
+    const position = getScrollPosition()
+    const shouldScroll = behavior.call(
+      router,
+      to,
+      from,
+      isPop ? position : null
+    )
+
+    if (!shouldScroll) {
+      return
+    }
+
+    if (typeof shouldScroll.then === 'function') {
+      shouldScroll
+        .then(shouldScroll => {
+          scrollToPosition((shouldScroll: any), position)
+        })
+        .catch(err => {
+          if (process.env.NODE_ENV !== 'production') {
+            assert(false, err.toString())
+          }
+        })
+    } else {
+      scrollToPosition(shouldScroll, position)
+    }
+  })
+}
+
+export function saveScrollPosition () {
+  const key = getStateKey()
+  if (key) {
+    positionStore[key] = {
+      x: window.pageXOffset,
+      y: window.pageYOffset
+    }
+  }
+}
+
+function handlePopState (e) {
+  saveScrollPosition()
+  if (e.state && e.state.key) {
+    setStateKey(e.state.key)
+  }
+}
+
+function getScrollPosition (): ?Object {
+  const key = getStateKey()
+  if (key) {
+    return positionStore[key]
+  }
+}
+
+function getElementPosition (el: Element, offset: Object): Object {
+  const docEl: any = document.documentElement
+  const docRect = docEl.getBoundingClientRect()
+  const elRect = el.getBoundingClientRect()
+  return {
+    x: elRect.left - docRect.left - offset.x,
+    y: elRect.top - docRect.top - offset.y
+  }
+}
+
+function isValidPosition (obj: Object): boolean {
+  return isNumber(obj.x) || isNumber(obj.y)
+}
+
+function normalizePosition (obj: Object): Object {
+  return {
+    x: isNumber(obj.x) ? obj.x : window.pageXOffset,
+    y: isNumber(obj.y) ? obj.y : window.pageYOffset
+  }
+}
+
+function normalizeOffset (obj: Object): Object {
+  return {
+    x: isNumber(obj.x) ? obj.x : 0,
+    y: isNumber(obj.y) ? obj.y : 0
+  }
+}
+
+function isNumber (v: any): boolean {
+  return typeof v === 'number'
+}
+
+const hashStartsWithNumberRE = /^#\d/
+
+function scrollToPosition (shouldScroll, position) {
+  const isObject = typeof shouldScroll === 'object'
+  if (isObject && typeof shouldScroll.selector === 'string') {
+    // getElementById would still fail if the selector contains a more complicated query like #main[data-attr]
+    // but at the same time, it doesn't make much sense to select an element with an id and an extra selector
+    const el = hashStartsWithNumberRE.test(shouldScroll.selector) // $flow-disable-line
+      ? document.getElementById(shouldScroll.selector.slice(1)) // $flow-disable-line
+      : document.querySelector(shouldScroll.selector)
+
+    if (el) {
+      let offset =
+        shouldScroll.offset && typeof shouldScroll.offset === 'object'
+          ? shouldScroll.offset
+          : {}
+      offset = normalizeOffset(offset)
+      position = getElementPosition(el, offset)
+    } else if (isValidPosition(shouldScroll)) {
+      position = normalizePosition(shouldScroll)
+    }
+  } else if (isObject && isValidPosition(shouldScroll)) {
+    position = normalizePosition(shouldScroll)
+  }
+
+  if (position) {
+    // $flow-disable-line
+    if ('scrollBehavior' in document.documentElement.style) {
+      window.scrollTo({
+        left: position.x,
+        top: position.y,
+        // $flow-disable-line
+        behavior: shouldScroll.behavior
+      })
+    } else {
+      window.scrollTo(position.x, position.y)
+    }
+  }
+}