src/utilities/ArrayUtility.js

/**
 * http://stackoverflow.com/a/13319168
 * arr1 and arr2 are arrays of any length; eqFn is a function which
 * can compare two items and return true if they're equal and false otherwise
 * @param {Array} arr1 - Array of any length
 * @param {Array} arr2 - Array of any length
 * @param {Function<Boolean>} eqFn - Function which returns a Boolean
 */
function union(arr1, arr2, eqFn) {
  return unique(arr1.concat(arr2), eqFn);
}

/**
 * Returns an array with unique values given the Eq Function
 * @param {Array} arr - Array that may contain duplicates
 * @param {Function<Boolean>} eqFn - A function that returns a Boolean
 */
function unique(arr, eqFn) {
  for (let i = 0; i < arr.length; i++) {
    for (let j = i + 1; j < arr.length; j++) {
      if (eqFn(arr[i], arr[j])) {
        arr.splice(j, 1);
        j--;
      }
    }
  }
  return arr;
}

/**
 * Convert the Array to an object
 *
 * @param  {Array}  _array    - The array to convert to an object
 * @param  {Object} [options] - Options on how to conver the array
 * @return {Object}           - The resulting object from the array
 */
function arrayToObject(_array, options = undefined) {
  const _obj = {};
  let i = 0;
  _array.forEach((obj) => {
    const key = (options && options.key) ? obj[options.key] : obj.id || ++i;
    if (key !== undefined && key !== null) {
      _obj[key] = obj;
    }
  });
  return _obj;
}

export { union, unique, arrayToObject };