Short JavaScript function required

I need a script creating that sets a variable based on various browser viewport dimensions. Theres 15 variants to consider, basically a big IF and OR statement. If the browser viewport height is X and the browser viewport width is Y then set Z to ABC, OR if browser viewport height is D and the browser viewport width is K then set Z to FGH etc until all the variants are considered. The variants are: Layout 1 - w 767 or less and h 864 or less Layout 2 - w 768 to 1023 and h 864 or less Layout 3 - w 1024 to 1279 and h 864 or less Layout 4 - w 1280 to 1599 and h 864 or less Layout 5 - w 1600 or more and h 864 or less Layout 6 - w 767 or less and h 865 to 1079 Layout 7 - w 768 to 1023 and h 865 to 1079 Layout 8 - w 1024 to 1279 and h 865 to 1079 Layout 9 - w 1280 to 1599 and h 865 to 1079 Layout 10 - w 1600 or more and h 865 to 1079 Layout 11 - w 767 or less and h 1080 or more Layout 12 - w 768 to 1023 and h 1080 or more Layout 13 - w 1024 to 1279 and h 1080 or more Layout 14 - w 1280 to 1599 and h 1080 or more Layout 15 - w 1600 or more and h 1080 or more