The above four objects are all in the vuex plug-in store, which is often used to store some data shared globally. But I still feel a little uncomfortable when using it, that is, I wrote a lot of repeated prefixes. At this time, these four objects appeared, which solved this pain point very well. mapState is mainly used to manipulate and obtain data, mapGetters is equivalent to computed properties, and mapMutations and mapActions are simplifications of mutation and action. They can be written as both objects and arrays.