Gets an array of repeated elements between two arrays

repeatedValues.js

/**
 * Gets all repeated values between two arrays
 *
 * @param  {Array} array1: array to compare
 * @param  {Array} array2: array to compare
 * @return {Array}
 */
function repeatedValues(array1, array2) {
  return array1.reduce((repeated, value) => {
    if (~array2.indexOf(value) && !~repeated.indexOf(value)) {
      repeated.push(value);
    }
    return repeated;
  }, []);
}

test.js

var a = [1, 5, 8, 5];
var b = [7, 8, 3];

repeatedValues(a, b);
// expected:
// [8]