js-fns/union/index.js

Modern JavaScript utility library focused on the build size

'use strict'

exports.default = union

/**
 * Creates a new array with all unique elements from the given arrays.
 *
 * @param arrays - The array of arrays of elements to get unique elements from
 * @returns An array with all unique elements from the given arrays
 *
 * @category Array
 * @public
 */
function union() {
  var uniqueSet = new Set()
  var result = []

  for (var arrayIndex = 0; arrayIndex < arguments.length; arrayIndex++) {
    var array =
      arrayIndex < 0 || arguments.length <= arrayIndex
        ? undefined
        : arguments[arrayIndex]

    for (var elementIndex = 0; elementIndex < array.length; elementIndex++) {
      var element = array[elementIndex]

      if (!uniqueSet.has(element)) {
        uniqueSet.add(element)
        result.push(element)
      }
    }
  }

  return result
}