Unique Array Helper

[MB-web]

Consider adding a helper function for creating duplicate-free versions of arrays.
Should only be needed for object arrays since for arrays whose items are of primitive type new Set() can be used directly.

Input of Daniel Rotter was we could also consider adding a library like Underscore.js or Ramda.js for such js utility.

/**
 * Produces a duplicate-free version of an object array, using `new Set()` for test equality.
 * Not meant to be used for array which items are of primitive type.
 */
export default function<T>(input: T[]): T[] {
  if (!Array.isArray(input)) {
    return [];
  }

  return [...new Set(input.map(element => JSON.stringify(element)))].map(element => JSON.parse(element)) as T[];
}