dedupe() - Takes an array and removes all of the duplicate values determined by the specified hash function. This can be used to make an array of unique values but the uniqueness should rely more on underlying values or properties.

dedupe.js

/**
 * Takes an array and removes all of the duplicate values determined by the
 * specified hash function.
 * @template {any[]} T
 * @param {T} array
 * @param {(value: T[number], index: number, array: T) => any} hash 
 * @returns {T}
 */
function dedupe(array, hash) {
  const hashedValues = new Set();
  return array.filter((value, index, array) => {
    const hashedValue = hash(value, index, array);
    const keepValue = !hashedValues.has(hashedValue);
    if (keepValue) {
      hashedValues.add(hashedValue);
    }
    return keepValue;
  });
}