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.
To enter or modify the command in a command block, use the Use Item control on the command block to open the command block GUI (graphical user interface). The GUI will only open if the player is in creative mode, and has the proper permissions. In singleplayer, cheats must be enabled to edit command blocks.