let myArray = ['a', 'b', 'a', 'b', 'c', 'e', 'e', 'c', 'd', 'd', 'd', 'd']
let myOrderedArray = myArray.reduce(function (acc, currentValue) {
  if (!acc.includes(currentValue)) {
    acc.push(currentValue)
  }
  return acc
}, [])

console.log(myOrderedArray)