function mergeArrays(a, b) {
	const merged = a.slice()

	for (const element of b) {
		if (a.indexOf(element) < 0) {
			merged.push(element)
		}
	}

	return merged.sort((a, b) => a - b)

	// ES6 version, requires Set polyfill.
	// let merged = new Set(a)
	// for (const element of b) {
	// 	merged.add(i)
	// }
	// return Array.from(merged).sort((a, b) => a - b)
}
Merges two arrays.
@param  {*} a
@param  {*} b
@return {*}