Knockout includes a function called ko.isObservable() . You can call it like ko.isObservable(vm[key]) . Update from comment: Here is a function to determine if something is a computed observable: UPDATE: If you are using KO 2.1+ - then you can use ko.isComputed directly.
Command Block. The Command Block is a redstone-powered block that was made available in the 1.4 update for Minecraft. The Command Block will perform server Commands when attached to a redstone circuit. This block cannot be crafted, and only server operators are allowed to place and use them.
Update: April fools! Hopefully releasing within the next two months, this 2-years-in-development game will be bringing blocky simulation games to the next level. Whilst based off the original Minecraft engine, this new version completely overhauls major parts of the game and contains many weeks worth of new content and blocks.