How to create a Set from Array and remove original items in JavaScript

Question

I have an Array with duplicate values.

I want to create a Set to get the distinct values of that array and remove or create a new Array that will have the same data MINUS the elements required to create the Set.

This is not just a matter of remove the duplicates, but remove a SINGLE entry of a each distinct value in the original array

Something like that works, but I wonder if there is a more direct approach:

let originalValues = [
  'a',
  'a',
  'a',
  'b',
  'b',
  'c',
  'c',
  'd'
];

let distinct = new Set(originalValues);
/*
distinct -> { 'a', 'b', 'c', 'd' }
*/

// Perhaps originalValues.extract(distinct) ??
for (let val of distinct.values()) {
  const index = originalValues.indexOf(val);
  originalValues.splice(index, 1);
}

/* 
originalValues -> [
  'a',
  'a',
  'b',
  'c'
];
*/

Answer 1

Use Array#filter in combination with the Set:

const originalValues = ['a', 'a', 'a', 'b', 'b', 'c',  'c', 'd'];

const remainingValues = originalValues.filter(function(val) {
  if (this.has(val)) { // if the Set has the value
    this.delete(val); // remove it from the Set
    return false; // filter it out
  }

  return true;
}, new Set(originalValues));



console.log(remainingValues);