const array1 = ['a', 'b', 'c', 'd']; const array2 = ['e', 'r', 's']; function commons(arr1, arr2) { let map = {}; for (let i=0; i < arr1.length; i++) { if (!map[array1[i]]){ const item = array1[i]; map[item] = true; } } for (let j=0; j < arr2.length; j++) { if (map[array2[j]]) { return true; } } return false }; commons(array1, array2)