isUnknownTag.js

// copy from https://github.com/vuejs/vue/blob/v2.0.1/src/shared/util.js
/**
 * Make a map and return a function for checking if a key
 * is in that map.
 */
export function makeMap (
  str: string,
  expectsLowerCase?: boolean
): (key: string) => true | void {
  const map = Object.create(null)
  const list: Array<string> = str.split(',')
  for (let i = 0; i < list.length; i++) {
    map[list[i]] = true
  }
  return expectsLowerCase
    ? val => map[val.toLowerCase()]
    : val => map[val]
}



// copy from https://github.com/vuejs/vue/blob/v2.0.1/src/platforms/web/util/element.js
const isHTMLTag = makeMap(
  'html,body,base,head,link,meta,style,title,' +
  'address,article,aside,footer,header,h1,h2,h3,h4,h5,h6,hgroup,nav,section,' +
  'div,dd,dl,dt,figcaption,figure,hr,img,li,main,ol,p,pre,ul,' +
  'a,b,abbr,bdi,bdo,br,cite,code,data,dfn,em,i,kbd,mark,q,rp,rt,rtc,ruby,' +
  's,samp,small,span,strong,sub,sup,time,u,var,wbr,area,audio,map,track,video,' +
  'embed,object,param,source,canvas,script,noscript,del,ins,' +
  'caption,col,colgroup,table,thead,tbody,td,th,tr,' +
  'button,datalist,fieldset,form,input,label,legend,meter,optgroup,option,' +
  'output,progress,select,textarea,' +
  'details,dialog,menu,menuitem,summary,' +
  'content,element,shadow,template'
)
// this map is intentionally selective, only covering SVG elements that may
// contain child elements.
export const isSVG = makeMap(
  'svg,animate,circle,clippath,cursor,defs,desc,ellipse,filter,font,' +
  'font-face,g,glyph,image,line,marker,mask,missing-glyph,path,pattern,' +
  'polygon,polyline,rect,switch,symbol,text,textpath,tspan,use,view',
  true
)
const isReservedTag = (tag: string): ?boolean => {
  return isHTMLTag(tag) || isSVG(tag)
}

const unknownElementCache = Object.create(null)
export function isUnknownElement (tag: string): boolean {
  /* istanbul ignore if */
  if (!inBrowser) {
    // TODO
    return true
  }
  if (isReservedTag(tag)) {
    return false
  }
  tag = tag.toLowerCase()
  /* istanbul ignore if */
  if (unknownElementCache[tag] != null) {
    return unknownElementCache[tag]
  }
  const el = document.createElement(tag)
  if (tag.indexOf('-') > -1) {
    // http://stackoverflow.com/a/28210364/1070244
    return (unknownElementCache[tag] = (
      el.constructor === window.HTMLUnknownElement ||
      el.constructor === window.HTMLElement
    ))
  } else {
    return (unknownElementCache[tag] = /HTMLUnknownElement/.test(el.toString()))
  }
}