Vuex getters和state在actions和getters中的最佳实践

Vuex getters and state usage in actions and getters

In Vuex, getters provide computed or derived state values. However, there are some best practices to follow when using getters and state in actions and getters.

When to use getters.products vs. state.products

In actions or getters, you should use getters.products over state.products because:

• Reactivity: Getters are reactive, meaning they are updated automatically when the state changes. Using getters.products ensures you always get the latest values.
• Caching: Vuex caches getter results, so using getters.products can prevent unnecessary recomputations.

When to call getters multiple times vs. assigning to a variable

Whether to call getters.products multiple times or assign it to a variable depends on:

• Getter complexity: If the getter is simple, you can call it multiple times with minimal performance impact.
• Data stability: If the data is likely to change frequently, call the getter each time to ensure you have the latest values.
• Performance: If the getter is complex or the data changes infrequently, assigning it to a variable can improve performance.

Getters returning functions

Vuex getters can return functions, but there are considerations:

Use with caution for large data

Getters returning functions avoid caching. This can lead to performance issues when dealing with large datasets. Consider using actions and mutations to manually update the state in such cases.

Cache function results for small data

For small datasets, you can improve performance by assigning the returned function to a variable and caching the results.

When to use getter functions

Getter functions are useful for:

• Dynamically calculating values based on complex or changing data.
• Avoiding unnecessary recomputations when the data is unlikely to change.

Conclusion

• Use getters.products over state.products to ensure reactivity and caching.
• Call getters multiple times or assign to a variable depending on complexity and data stability.
• Use getter functions sparingly, and avoid them for large datasets.
• Consider using actions and mutations to update the state manually for complex or frequently changing data.

FAQs

1. When should I use getters vs. computed properties?
   Getters are better suited for state-related calculations, while computed properties are more appropriate for component-specific calculations.

2. How can I improve the performance of getters?
   Avoid complex getters and use getter functions sparingly. Assign frequently used getter results to variables.

3. Why are getter functions not cached?
   Caching getter functions would defeat the purpose of being able to dynamically calculate values based on changing data.

4. How do I use getters in actions?
   Actions can access getters using this.getters.getterName.

5. Can getters return promises?
   Yes, getters can return promises, allowing you to perform asynchronous operations and access data from external sources.