annotate platforms/web

flow/compiler.js

@@ -20,6 +20,13 @@ declare type ASTElementHandlers = {
 
 declare type ASTElementHooks = { [key: string]: Array<string> }
 
+declare type ASTDirective = {
+  name: string,
+  value: ?string,
+  arg: ?string,
+  modifiers: ?{ [key: string]: true }
+}
+
 declare type ASTText = {
   text?: string,
   expression?: string
@@ -70,12 +77,7 @@ declare type ASTElement = {
   transition?: string | true,
   transitionOnAppear?: boolean,
 
-  directives?: Array<{
-    name: string,
-    value: ?string,
-    arg: ?string,
-    modifiers: ?{ [key: string]: true }
-  }>,
+  directives?: Array<ASTDirective>,
 
   forbidden?: true,
   once?: true

flow/vnode.js

@@ -11,6 +11,7 @@ declare type VNodeComponentOptions = {
 declare interface MountedComponentVNode {
   componentOptions: VNodeComponentOptions;
   child: Component;
+  parent: VNode;
 }
 
 // interface for vnodes in update modules
@@ -19,10 +20,11 @@ declare interface VNodeWithData {
   data: VNodeData;
   children: Array<VNode> | void;
   text: void;
-  elm: Node;
+  elm: HTMLElement;
   ns: string | void;
   context: Component;
   key: string | number | void;
+  parent?: VNodeWithData;
 }
 
 declare interface VNodeData {
@@ -46,10 +48,12 @@ declare interface VNodeData {
     render: Function,
     staticRenderFns: Array<Function>
   };
-  directives?: Array<{
-    name: string,
-    value?: any,
-    arg?: string,
-    modifiers?: { [key: string]: boolean }
-  }>;
+  directives?: Array<VNodeDirective>;
+}
+
+declare type VNodeDirective = {
+  name: string,
+  value?: any,
+  arg?: string,
+  modifiers?: { [key: string]: boolean }
 }

src/compiler/directives/ref.js

@@ -2,7 +2,7 @@
 
 import { addHook } from '../helpers'
 
-export function ref (el: ASTElement, dir: { arg: string }) {
+export function ref (el: ASTElement, dir: ASTDirective) {
   // go up and check if this node is inside a v-for
   let isFor = false
   let parent = el

src/core/vdom/patch.js

@@ -310,7 +310,7 @@ export function createPatchFunction (backend) {
     }
     if (isDef(tag)) {
       if (isDef(children)) {
-        const childNodes = elm.childNodes
+        const childNodes = nodeOps.childNodes(elm)
         for (let i = 0; i < children.length; i++) {
           const success = hydrate(childNodes[i], children[i], insertedVnodeQueue)
           if (!success) {
@@ -330,10 +330,11 @@ export function createPatchFunction (backend) {
       if (vnode.tag.indexOf('vue-component') === 0) {
         return true
       } else {
-        return vnode.tag === node.tagName.toLowerCase() && (
+        const childNodes = nodeOps.childNodes(node)
+        return vnode.tag === nodeOps.tagName(node).toLowerCase() && (
           vnode.children
-            ? vnode.children.length === node.childNodes.length
-            : node.childNodes.length === 0
+            ? vnode.children.length === childNodes.length
+            : childNodes.length === 0
         )
       }
     } else {

src/entries/web-runtime-with-compiler.js

@@ -6,10 +6,13 @@ import { warn, cached } from 'core/util/index'
 import { query } from 'web/util/index'
 import { compileToFunctions } from './web-compiler'
 
-const idToTemplate = cached(id => query(id).innerHTML)
-const mount = Vue.prototype.$mount
+const idToTemplate = cached(id => {
+  const el = query(id)
+  return el && el.innerHTML
+})
 
-Vue.prototype.$mount = function (el?: string | Element): Vue {
+const mount = Vue.prototype.$mount
+Vue.prototype.$mount = function (el: string | Element): Component {
   el = el && query(el)
   const options = this.$options
   // resolve template/el and convert to render function

src/platforms/web/compiler/directives/html.js

@@ -1,6 +1,8 @@
+/* @flow */
+
 import { addProp } from 'compiler/helpers'
 
-export default function html (el, dir) {
+export default function html (el: ASTElement, dir: ASTDirective) {
   if (!dir.value) return
   addProp(el, 'innerHTML', `__toString__(${dir.value})`)
 }

src/platforms/web/compiler/directives/model.js

@@ -1,6 +1,8 @@
+/* @flow */
+
 import { addHandler, addProp, getBindingAttr } from 'compiler/helpers'
 
-export default function model (el, dir) {
+export default function model (el: ASTElement, dir: ASTDirective) {
   const value = dir.value
   const modifiers = dir.modifiers
   if (el.tag === 'select') {

src/platforms/web/compiler/directives/text.js

@@ -1,6 +1,8 @@
+/* @flow */
+
 import { addProp } from 'compiler/helpers'
 
-export default function text (el, dir) {
+export default function text (el: ASTElement, dir: ASTDirective) {
   if (!dir.value) return
   addProp(el, 'textContent', `__toString__(${dir.value})`)
 }

src/platforms/web/runtime/class-util.js

@@ -1,3 +1,5 @@
+/* @flow */
+
 import { isIE9, namespaceMap } from 'web/util/index'
 
 const svgNS = namespaceMap.svg
@@ -7,11 +9,8 @@ const svgNS = namespaceMap.svg
  * if the element also has the :class attribute; However in
  * PhantomJS, setting `className` does not work on SVG elements...
  * So we have to do a conditional check here.
- *
- * @param {Element} el
- * @param {String} cls
  */
-export function setClass (el, cls) {
+export function setClass (el: Element, cls: string) {
   /* istanbul ignore else */
   if (!isIE9 || el.namespaceURI === svgNS) {
     el.setAttribute('class', cls)
@@ -22,11 +21,8 @@ export function setClass (el, cls) {
 
 /**
  * Add class with compatibility for IE & SVG
- *
- * @param {Element} el
- * @param {String} cls
  */
-export function addClass (el, cls) {
+export function addClass (el: Element, cls: string) {
   if (el.classList) {
     if (cls.indexOf(' ') > -1) {
       cls.split(/\s+/).forEach(c => el.classList.add(c))
@@ -43,11 +39,8 @@ export function addClass (el, cls) {
 
 /**
  * Remove class with compatibility for IE & SVG
- *
- * @param {Element} el
- * @param {String} cls
  */
-export function removeClass (el, cls) {
+export function removeClass (el: Element, cls: string) {
   if (el.classList) {
     if (cls.indexOf(' ') > -1) {
       cls.split(/\s+/).forEach(c => el.classList.remove(c))
@@ -71,11 +64,8 @@ export function removeClass (el, cls) {
  * For IE9 compat: when both class and :class are present
  * getAttribute('class') returns wrong value... but className
  * on SVG elements returns an object.
- *
- * @param {Element} el
- * @return {String}
  */
-function getClass (el) {
+function getClass (el: Element): string {
   let classname = el.className
   if (typeof classname === 'object') {
     classname = classname.baseVal || ''

src/platforms/web/runtime/directives/model.js

@@ -1,3 +1,8 @@
+/**
+ * Not type checking this file because flow doesn't like attaching
+ * properties to Elements.
+ */
+
 import { isAndroid, isIE9 } from 'web/util/index'
 
 if (isIE9) {

src/platforms/web/runtime/directives/show.js

@@ -1,15 +1,17 @@
+/* @flow */
+
 import { isIE9 } from 'web/util/index'
 import { enter, leave } from '../modules/transition'
 
 export default {
-  bind (el, value, _, vnode) {
+  bind (el: HTMLElement, value: any, _: any, vnode: VNodeWithData) {
     const transition = getTransition(vnode)
     if (value && transition && transition.appea && !isIE9) {
       enter(vnode)
     }
     el.style.display = value ? '' : 'none'
   },
-  update (el, value, _, vnode) {
+  update (el: HTMLElement, value: any, _: any, vnode: VNodeWithData) {
     const transition = getTransition(vnode)
     if (transition && !isIE9) {
       if (value) {
@@ -26,7 +28,7 @@ export default {
   }
 }
 
-function getTransition (vnode) {
+function getTransition (vnode: VNodeWithData): Object | string | void {
   const parent = vnode.parent
   return parent && parent.data.transition != null
     ? parent.data.transition

src/platforms/web/runtime/modules/attrs.js

@@ -1,3 +1,5 @@
+/* @flow */
+
 import {
   isBooleanAttr,
   isEnumeratedAttr,
@@ -7,7 +9,7 @@ import {
   isFalsyAttrValue
 } from 'web/util/index'
 
-function updateAttrs (oldVnode, vnode) {
+function updateAttrs (oldVnode: VNodeWithData, vnode: VNodeWithData) {
   if (!oldVnode.data.attrs && !vnode.data.attrs) {
     return
   }
@@ -34,7 +36,7 @@ function updateAttrs (oldVnode, vnode) {
   }
 }
 
-function setAttr (el, key, value) {
+function setAttr (el: Element, key: string, value: any) {
   if (isBooleanAttr(key)) {
     // set attribute for blank value
     // e.g. <option disabled>Select one</option>
@@ -61,11 +63,10 @@ function setAttr (el, key, value) {
 }
 
 export default {
-  create: function (_, vnode) {
+  create: function (_: any, vnode: VNodeWithData) {
     const attrs = vnode.data.staticAttrs
     if (attrs) {
       for (const key in attrs) {
-        if (!vnode.elm) debugger
         setAttr(vnode.elm, key, attrs[key])
       }
     }

src/platforms/web/runtime/modules/class.js

@@ -1,9 +1,11 @@
+/* @flow */
+
 import { setClass } from '../class-util'
 import { genClassForVnode, concat, stringifyClass } from 'web/util/index'
 
-function updateClass (oldVnode, vnode) {
+function updateClass (oldVnode: any, vnode: any) {
   const el = vnode.elm
-  const data = vnode.data
+  const data: VNodeData = vnode.data
   if (!data.staticClass && !data.class) {
     return
   }

src/platforms/web/runtime/modules/events.js

@@ -1,6 +1,8 @@
+/* @flow */
+
 import { updateListeners } from 'core/vdom/helpers'
 
-function updateDOMListeners (oldVnode, vnode) {
+function updateDOMListeners (oldVnode: VNodeWithData, vnode: VNodeWithData) {
   if (!oldVnode.data.on && !vnode.data.on) {
     return
   }

src/platforms/web/runtime/modules/props.js

@@ -1,9 +1,11 @@
-function updateProps (oldVnode, vnode) {
+/* @flow */
+
+function updateProps (oldVnode: VNodeWithData, vnode: VNodeWithData) {
   if (!oldVnode.data.props && !vnode.data.props) {
     return
   }
   let key, cur, old
-  const elm = vnode.elm
+  const elm: any = vnode.elm
   const oldProps = oldVnode.data.props || {}
   const props = vnode.data.props || {}
 

src/platforms/web/runtime/modules/style.js

@@ -1,10 +1,12 @@
-import { extend, cached, camelize } from 'shared/util'
-import { inBrowser } from 'core/util/env'
+/* @flow */
+
+import { cached, camelize, toObject } from 'shared/util'
 
 const prefixes = ['Webkit', 'Moz', 'ms']
-const testEl = inBrowser && document.createElement('div')
 
+let testEl
 const normalize = cached(function (prop) {
+  testEl = testEl || document.createElement('div')
   prop = camelize(prop)
   if (prop !== 'filter' && (prop in testEl.style)) {
     return prop
@@ -18,13 +20,13 @@ const normalize = cached(function (prop) {
   }
 })
 
-function updateStyle (oldVnode, vnode) {
+function updateStyle (oldVnode: VNodeWithData, vnode: VNodeWithData) {
   if (!oldVnode.data.style && !vnode.data.style) {
     return
   }
   let cur, name
-  const elm = vnode.elm
-  const oldStyle = oldVnode.data.style || {}
+  const elm: any = vnode.elm
+  const oldStyle: any = oldVnode.data.style || {}
   let style = vnode.data.style || {}
 
   // handle array syntax
@@ -45,16 +47,6 @@ function updateStyle (oldVnode, vnode) {
   }
 }
 
-function toObject (arr) {
-  const res = arr[0] || {}
-  for (let i = 1; i < arr.length; i++) {
-    if (arr[i]) {
-      extend(res, arr[i])
-    }
-  }
-  return res
-}
-
 export default {
   create: updateStyle,
   update: updateStyle

src/platforms/web/runtime/modules/transition.js

@@ -1,27 +1,30 @@
+/* @flow */
+
 import { addClass, removeClass } from '../class-util'
 import { inBrowser, resolveAsset } from 'core/util/index'
 import { cached, remove } from 'shared/util'
 import { isIE9 } from 'web/util/index'
 
+const hasTransition = inBrowser && !isIE9
 const TRANSITION = 'transition'
 const ANIMATION = 'animation'
 
 // Transition property/event sniffing
-let transitionProp
-let transitionEndEvent
-let animationProp
-let animationEndEvent
-if (inBrowser && !isIE9) {
-  const isWebkitTrans =
-    window.ontransitionend === undefined &&
-    window.onwebkittransitionend !== undefined
-  const isWebkitAnim =
-    window.onanimationend === undefined &&
-    window.onwebkitanimationend !== undefined
-  transitionProp = isWebkitTrans ? 'WebkitTransition' : 'transition'
-  transitionEndEvent = isWebkitTrans ? 'webkitTransitionEnd' : 'transitionend'
-  animationProp = isWebkitAnim ? 'WebkitAnimation' : 'animation'
-  animationEndEvent = isWebkitAnim ? 'webkitAnimationEnd' : 'animationend'
+let transitionProp = 'transition'
+let transitionEndEvent = 'transitionend'
+let animationProp = 'animation'
+let animationEndEvent = 'animationend'
+if (hasTransition) {
+  if (window.ontransitionend === undefined &&
+    window.onwebkittransitionend !== undefined) {
+    transitionProp = 'WebkitTransition'
+    transitionEndEvent = 'webkitTransitionEnd'
+  }
+  if (window.onanimationend === undefined &&
+    window.onwebkitanimationend !== undefined) {
+    animationProp = 'WebkitAnimation'
+    animationEndEvent = 'webkitAnimationEnd'
+  }
 }
 
 const raf = (inBrowser && window.requestAnimationFrame) || setTimeout
@@ -31,8 +34,8 @@ function nextFrame (fn) {
   })
 }
 
-export function enter (vnode) {
-  const el = vnode.elm
+export function enter (vnode: VNodeWithData) {
+  const el: any = vnode.elm
   // call leave callback now
   if (el._leaveCb) {
     el._leaveCb.cancelled = true
@@ -89,8 +92,8 @@ export function enter (vnode) {
   }
 }
 
-export function leave (vnode, rm) {
-  const el = vnode.elm
+export function leave (vnode: VNodeWithData, rm: Function) {
+  const el: any = vnode.elm
   // call enter callback now
   if (el._enterCb) {
     el._enterCb.cancelled = true
@@ -145,7 +148,7 @@ export function leave (vnode, rm) {
   }
 }
 
-function resolveTransition (id, context) {
+function resolveTransition (id: string | Object, context: Component): Object {
   let definition = id && typeof id === 'string'
     ? resolveAsset(context.$options, 'transitions', id) || id
     : id
@@ -155,7 +158,7 @@ function resolveTransition (id, context) {
     : definition
 }
 
-const autoCssTransition = cached(name => {
+const autoCssTransition: (name: string) => Object = cached(name => {
   return {
     enterClass: `${name}-enter`,
     leaveClass: `${name}-leave`,
@@ -164,17 +167,17 @@ const autoCssTransition = cached(name => {
   }
 })
 
-function addTransitionClass (el, cls) {
+function addTransitionClass (el: any, cls: string) {
   (el._transitionClasses || (el._transitionClasses = [])).push(cls)
   addClass(el, cls)
 }
 
-function removeTransitionClass (el, cls) {
+function removeTransitionClass (el: any, cls: string) {
   remove(el._transitionClasses, cls)
   removeClass(el, cls)
 }
 
-function whenTransitionEnds (el, cb) {
+function whenTransitionEnds (el: Element, cb: Function) {
   const { type, timeout, propCount } = getTransitionInfo(el)
   if (!type) return cb()
   const event = type === TRANSITION ? transitionEndEvent : animationEndEvent
@@ -196,7 +199,11 @@ function whenTransitionEnds (el, cb) {
   el.addEventListener(event, onEnd)
 }
 
-function getTransitionInfo (el) {
+function getTransitionInfo (el: Element): {
+  type: ?string,
+  propCount: number,
+  timeout: number
+} {
   const styles = window.getComputedStyle(el)
   // 1. determine the maximum duration (timeout)
   const transitioneDelays = styles[transitionProp + 'Delay'].split(', ')
@@ -223,17 +230,17 @@ function getTransitionInfo (el) {
   }
 }
 
-function getTimeout (delays, durations) {
+function getTimeout (delays: Array<string>, durations: Array<string>): number {
   return Math.max.apply(null, durations.map((d, i) => {
     return toMs(d) + toMs(delays[i])
   }))
 }
 
-function toMs (s) {
+function toMs (s: string): number {
   return Number(s.slice(0, -1)) * 1000
 }
 
-function once (fn) {
+function once (fn: Function): Function {
   let called = false
   return () => {
     if (!called) {
@@ -243,8 +250,8 @@ function once (fn) {
   }
 }
 
-function shouldSkipTransition (vnode) {
-  return (
+function shouldSkipTransition (vnode: VNodeWithData): boolean {
+  return !!(
     // if this is a component root node and the compoennt's
     // parent container node also has transition, skip.
     (vnode.parent && vnode.parent.data.transition) ||
@@ -254,17 +261,17 @@ function shouldSkipTransition (vnode) {
   )
 }
 
-export default !transitionEndEvent ? {} : {
-  create: function (_, vnode) {
+export default hasTransition ? {
+  create: function (_: any, vnode: VNodeWithData) {
     if (!shouldSkipTransition(vnode)) {
       enter(vnode)
     }
   },
-  remove: function (vnode, rm) {
+  remove: function (vnode: VNode, rm: Function) {
     if (!shouldSkipTransition(vnode)) {
       leave(vnode, rm)
     } else {
       rm()
     }
   }
-}
+} : {}

src/platforms/web/runtime/node-ops.js

@@ -1,41 +1,47 @@
+/* @flow */
+
 import { namespaceMap } from 'web/util/index'
 
-export function createElement (tagName) {
+export function createElement (tagName: string): Element {
   return document.createElement(tagName)
 }
 
-export function createElementNS (namespace, tagName) {
+export function createElementNS (namespace: string, tagName: string): Element {
   return document.createElementNS(namespaceMap[namespace], tagName)
 }
 
-export function createTextNode (text) {
+export function createTextNode (text: string): Text {
   return document.createTextNode(text)
 }
 
-export function insertBefore (parentNode, newNode, referenceNode) {
+export function insertBefore (parentNode: Node, newNode: Node, referenceNode: Node) {
   parentNode.insertBefore(newNode, referenceNode)
 }
 
-export function removeChild (node, child) {
+export function removeChild (node: Node, child: Node) {
   node.removeChild(child)
 }
 
-export function appendChild (node, child) {
+export function appendChild (node: Node, child: Node) {
   node.appendChild(child)
 }
 
-export function parentNode (node) {
+export function parentNode (node: Node): ?Element {
   return node.parentElement
 }
 
-export function nextSibling (node) {
+export function nextSibling (node: Node): Node {
   return node.nextSibling
 }
 
-export function tagName (node) {
+export function tagName (node: Element): string {
   return node.tagName
 }
 
-export function setTextContent (node, text) {
+export function setTextContent (node: Node, text: string) {
   node.textContent = text
 }
+
+export function childNodes (node: Node): NodeList {
+  return node.childNodes
+}

src/platforms/web/server/directives/show.js

@@ -1,5 +1,8 @@
-export default function show (node, dir) {
+/* @flow */
+
+export default function show (node: VNodeWithData, dir: VNodeDirective) {
   if (!dir.value) {
-    (node.data.style || (node.data.style = {})).display = 'none'
+    const style: any = node.data.style || (node.data.style = {})
+    style.display = 'none'
   }
 }

src/platforms/web/server/modules/attrs.js

@@ -1,3 +1,5 @@
+/* @flow */
+
 import {
   isBooleanAttr,
   isEnumeratedAttr,
@@ -5,7 +7,7 @@ import {
   propsToAttrMap
 } from 'web/util/index'
 
-export default function renderAttrs (node) {
+export default function renderAttrs (node: VNodeWithData): ?string {
   if (node.data.attrs || node.data.props || node.data.staticAttrs) {
     return (
       serialize(node.data.staticAttrs) +
@@ -15,7 +17,7 @@ export default function renderAttrs (node) {
   }
 }
 
-function serialize (attrs, asProps) {
+function serialize (attrs: ?{ [key: string]: any }, asProps?: boolean): string {
   let res = ''
   if (!attrs) {
     return res

src/platforms/web/server/modules/class.js

@@ -1,6 +1,8 @@
+/* @flow */
+
 import { genClassForVnode } from 'web/util/index'
 
-export default function renderClass (node) {
+export default function renderClass (node: VNodeWithData): ?string {
   if (node.data.class || node.data.staticClass) {
     return ` class="${genClassForVnode(node)}"`
   }

src/platforms/web/server/modules/style.js

@@ -1,12 +1,19 @@
-import { hyphenate } from 'shared/util'
+/* @flow */
 
-export default function renderStyle (node) {
+import { hyphenate, toObject } from 'shared/util'
+
+export default function renderStyle (node: VNodeWithData): ?string {
   const staticStyle = node.data.staticAttrs && node.data.staticAttrs.style
   if (node.data.style || staticStyle) {
-    const styles = node.data.style
+    let styles = node.data.style
     let res = ' style="'
-    for (const key in styles) {
-      res += `${hyphenate(key)}:${styles[key]};`
+    if (styles) {
+      if (Array.isArray(styles)) {
+        styles = toObject(styles)
+      }
+      for (const key in styles) {
+        res += `${hyphenate(key)}:${styles[key]};`
+      }
     }
     return res + (staticStyle || '') + '"'
   }

src/platforms/web/util/attrs.js

@@ -1,3 +1,5 @@
+/* @flow */
+
 import { makeMap } from 'shared/util'
 
 // attributes that should be using props for binding
@@ -22,6 +24,15 @@ export const propsToAttrMap = {
 }
 
 export const xlinkNS = 'http://www.w3.org/1999/xlink'
-export const isXlink = name => name.charAt(5) === ':' && name.slice(0, 5) === 'xlink'
-export const getXlinkProp = name => isXlink(name) ? name.slice(6, name.length) : ''
-export const isFalsyAttrValue = val => val == null || val === false
+
+export const isXlink = (name: string): boolean => {
+  return name.charAt(5) === ':' && name.slice(0, 5) === 'xlink'
+}
+
+export const getXlinkProp = (name: string): string => {
+  return isXlink(name) ? name.slice(6, name.length) : ''
+}
+
+export const isFalsyAttrValue = (val: any): boolean => {
+  return val == null || val === false
+}

src/platforms/web/util/class.js

@@ -1,6 +1,8 @@
+/* @flow */
+
 import { extend, isObject } from 'shared/util'
 
-export function genClassForVnode (vnode) {
+export function genClassForVnode (vnode: VNode): string {
   let data = vnode.data
   // Important: check if this is a component container node
   // or a child component root node
@@ -14,44 +16,50 @@ export function genClassForVnode (vnode) {
   return genClassFromData(data)
 }
 
-function mergeClassData (child, parent) {
+function mergeClassData (child: VNodeData, parent: VNodeData): {
+  staticClass: string,
+  class: ?Object
+} {
   return {
     staticClass: concat(child.staticClass, parent.staticClass),
-    class: child.class ? extend(child.class, parent.class) : parent.class
+    class: child.class
+      ? extend(child.class, parent.class)
+      : parent.class
   }
 }
 
-function genClassFromData (data) {
+function genClassFromData (data: Object): string {
   const dynamicClass = data.class
   const staticClass = data.staticClass
   if (staticClass || dynamicClass) {
     return concat(staticClass, stringifyClass(dynamicClass))
   }
+  return ''
 }
 
-export function concat (a, b) {
+export function concat (a: ?string, b: ?string): string {
   return a ? b ? (a + ' ' + b) : a : (b || '')
 }
 
-export function stringifyClass (value) {
+export function stringifyClass (value: any): string {
+  let res = ''
   if (!value) {
-    return ''
+    return res
   }
   if (typeof value === 'string') {
     return value
   }
   if (Array.isArray(value)) {
-    let res = ''
     for (let i = 0, l = value.length; i < l; i++) {
       if (value[i]) res += stringifyClass(value[i]) + ' '
     }
     return res.slice(0, -1)
   }
   if (isObject(value)) {
-    let res = ''
     for (const key in value) {
       if (value[key]) res += key + ' '
     }
     return res.slice(0, -1)
   }
+  return res
 }

src/platforms/web/util/element.js

@@ -1,3 +1,5 @@
+/* @flow */
+
 import { inBrowser } from 'core/util/env'
 import { makeMap } from 'shared/util'
 
@@ -51,7 +53,7 @@ const isSVG = makeMap(
   true
 )
 
-export function getTagNamespace (tag) {
+export function getTagNamespace (tag: string): ?string {
   if (isSVG(tag)) {
     return 'svg'
   }
@@ -63,7 +65,7 @@ export function getTagNamespace (tag) {
 }
 
 const unknownElementCache = Object.create(null)
-export function isUnknownElement (tag) {
+export function isUnknownElement (tag: string): boolean {
   if (!inBrowser) {
     return true
   }

src/platforms/web/util/index.js

@@ -1,3 +1,5 @@
+/* @flow */
+
 import { warn, inBrowser } from 'core/util/index'
 
 export * from './attrs'
@@ -10,11 +12,8 @@ export const isAndroid = UA && UA.indexOf('android') > 0
 
 /**
  * Query an element selector if it's not an element already.
- *
- * @param {String|Element} el
- * @return {Element}
  */
-export function query (el) {
+export function query (el: string | Element): Element {
   if (typeof el === 'string') {
     const selector = el
     el = document.querySelector(el)
@@ -22,6 +21,7 @@ export function query (el) {
       process.env.NODE_ENV !== 'production' && warn(
         'Cannot find element: ' + selector
       )
+      return document.createElement('div')
     }
   }
   return el

src/shared/util.js

@@ -127,7 +127,7 @@ export function toArray (list: any, start?: number): Array<any> {
 /**
  * Mix properties into target object.
  */
-export function extend (to: Object, _from: Object): Object {
+export function extend (to: Object, _from: ?Object): Object {
   for (const key in _from) {
     to[key] = _from[key]
   }
@@ -153,6 +153,19 @@ export function isPlainObject (obj: any): boolean {
   return toString.call(obj) === OBJECT_STRING
 }
 
+/**
+ * Merge an Array of Objects into a single Object.
+ */
+export function toObject (arr: Array<any>): Object {
+  const res = arr[0] || {}
+  for (let i = 1; i < arr.length; i++) {
+    if (arr[i]) {
+      extend(res, arr[i])
+    }
+  }
+  return res
+}
+
 /**
  * Perform no operation.
  */