удалить все дубликаты из массива
const removeDuplicates = arr => [...new Set(arr)];
Graceful Grasshopper
const removeDuplicates = arr => [...new Set(arr)];const numbers = [1 , 21, 21, 34 ,12 ,34 ,12];
const removeRepeatNumbers = array => [... new Set(array)]
removeRepeatNumbers(numbers) // [ 1, 21, 34, 12 ]// removeDuplicates ES6
const uniqueArray = oldArray.filter((item, index, self) => self.indexOf(item) === index);
let myArray = ['a', 'b', 'a', 'b', 'c', 'e', 'e', 'c', 'd', 'd', 'd', 'd']
let myOrderedArray = myArray.reduce(function (accumulator, currentValue) {
if (accumulator.indexOf(currentValue) === -1) {
accumulator.push(currentValue)
}
return accumulator
}, [])
console.log(myOrderedArray)