What is observable in MobX?

Autorun works by running the effect in a reactive context . During the execution of the provided function, MobX keeps track of all observable and computed values that are directly or indirectly read by the effect.

observable defines a trackable field that stores the state . action marks a method as action that will modify the state. computed marks a getter that will derive new facts from the state and cache its output.

Computed values can be created by annotating JavaScript getters with computed . Use makeObservable to declare a getter as computed. If you instead want all getters to be automatically declared as computed , you can use either makeAutoObservable , observable or extendObservable .