function mergeArrays(arr1, arr2) {
	let commonArray = arr1.concat(arr2);
	let sortComArr = commonArray.sort((a, b) => a - b);
	let result = sortComArr.filter((current, i) => {
		return sortComArr.indexOf(current) === i;
	})
	return result
}

console.log(mergeArrays([1, 1, 3, 5, 7, 9], [10, 8, 6, 4, 2]))