Vuex 3

Source

• vuex documentation

Introduction

• state management pattern + library for Vue
• for medium to large scale SPA
• solve problems
  • multiple views depending on same piece of state
  • actions from different views need to mutate the same piece of state
• reactive
• can only mutate state through commiting mutations

Core Concepts

State

• single state tree, so one store for each application
• provide store in root instance to inject store into all child components. Can be access through this.$store
• mapState is for mapping multiple store state properties ('count' = map this.count to store.state.count)
• spread it when use with local computed properties

Getters

• like computed property for store. When we need to value from computing a state
• evaluate based on dependencies
• access via this.$store.getters
• arguments: state, getters?
• method-syle allows passing arguments to getter
• spread mapGetters in computed

Mutations

• only way to change state
• has a type and a handler (perform actual state modification)
• store.commit(<type>, payload?) OR store.commit(type: <type>, <payload>: value). payload should be an object
• follows reactivity rules
  • initial state
  • Vue.set OR replace the whole object
• constant for type in large project
• must be synchronous
• mapMutations

Actions

• commit mutations
• can be asynchronous
• receive context object and also payload?
• store.dispatch
• mapActions
• can then on dispatch to chain actions

Modules

• each module can has its own store, even nested modules
• local state is the first argument.
• actions has context.state and context.rootState (arguments: state, commit, rootState?, rootGetters?). Same thing for getters
• actions, mutations, and getters are registered under the global namespace. Use namespace:true to registers them under module
• pass {root: true} as third argument to dispatch and commit to trigger actions in the global namespace
• can register global actions in namespaced module using handler and {root:true}
• can pass module namespace when mapping to save keystrokes OR createNamespaceHelpers
• look out for namespace when developing plugin
• store.registerModule to register a module after store is created. Can unregisterModule and hasModule
• preserveState

Advanced

Application Structure

• store has the application-level state
• only mutate using mutation and keep it sync
• use actions to do async stuff

Plugins

• plugins when creating store
• a function that only receives store

Strict Mode

• strict:true
• do not enable for production because can be expensive

Form Handling

• bind value and @input OR get and set

Testing

• mutation: export mutation itself
• action: mock
• getter: same as mutation

Hot Reloading

• supports hot-reloading mutations, modules, actions and getters during development