What are mutations in Vuex and what are they for?
Vuex mutations are essential for updating the state of an application in Vue. They do not update the state directly; instead, they allow you to log and track all applied changes, facilitating code debugging. This is crucial when multiple components modify state simultaneously, as it helps determine which component is making specific changes.
How do mutations work similar to events?
Mutations are defined in the store
, and act as event handlers. Vue components execute these mutations using the commit
method, which is equivalent to the emit
method of events. This method specifies the name of the mutation to be executed, which allows the change to be registered and the state to be updated.
//mutations: { increment: (state) => state.count++, decrement: (state) => state.count--,}
How are mutations implemented in a Vue component?
- In the Vue component, the
commit
method is used to call mutations:
methods: { increment() { this.$store.commit('increment'); }, decrement() { this.$store.commit('decrement'); } }}
- So, when the related buttons are clicked, the
count
value in the state is updated and the component is automatically updated to reflect these changes.
What are payloads in a mutation?
In mutations, a payload
can be used to pass configurable parameters to the state. Usually, this is an object that allows to carry more than one parameter, providing flexibility and customization in the operations.
Example with payloads
Suppose we need to increment the count
value by a specific number:
{mutations: { increment(state, payload = { number: 1 }) { state.count += payload.number; } }}
In this code fragment, when not receiving a payload
, an empty object is allocated by default to avoid errors.
Implementation in a component
In the Vue component, it can be adapted to handle custom increments:
{methods: { increment(payload) { this.$store.commit('increment', payload); } }this.increment({ number: 10 });
How to use mapMutations to optimize the code?
Vuex offers mapMutations
, which allows to extract the mutations already defined in the store
, avoiding code duplication in each component.
Implementing mapMutations
import { mapMutations } from 'vuex';
export default { methods: {...mapMutations(['increment', 'decrement']), incrementTen() { this.$store.commit('increment', { number: 10 }); } } } }}
With mapMutations
, it is possible to combine store
methods with those customized in the component, optimizing state management and code reuse.
If incrementTen
needs to be used in multiple places, it can be brought into the store
to improve accessibility and consistency.
Vuex and mutations provide a systematic way to manage data flow in Vue applications, making state management clearer and more efficient. By understanding and correctly applying these concepts, developers can build reactive and scalable applications more efficiently.
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