intersect-obj-hash.js

const intersectObjHash = ( a, b ) => {
  const hash = {}

  for ( let i = 0; i < b.length; i++ ) {
    hash[ b[ i ] ] = true
  }

  return a.filter( el => hash[ el ] )
}

intersect-set-hash.js

const intersectSetHash = ( a, b ) => {
  const hash = new Set( b )

  return a.filter( el => hash.has( el ) )
}