SOURCE

let tags = 'div,p,img,ul,li'.split(',')

function makeMap ( keys ) {
  let set = {}
  console.log( keys )
  keys.forEach( item => {
    set[item] = true
  })
  return function ( pary ) {
    return !!set[ pary.toLowerCase() ]
  }
}

let isHTMLTag = makeMap( tags )

let hasDIV = isHTMLTag( 'div' )

let hasP = isHTMLTag( 'p' )

let hasHL = isHTMLTag( 'hl' )

console.log( hasDIV )

console.log( hasP )

console.log( hasHL )