Revealing the implementation principles and optimization solutions of computed in Vue

Vue is an extremely popular JavaScript framework favored by many developers. Its core features are reactive data and data binding. In Vue, computed is an enhancement to responsive data and is widely used. This article will analyze the implementation principle of computed in detail, and improve the performance and experience of Vue applications through optimized practical solutions.

The implementation principle of computed

Computed is a computed property in Vue. The essence of a computed property is a function, and the result is obtained by calculating the responsive data. It is implemented based on Vue's reactive system, which means computed will automatically recalculate new results when dependent data changes.

The implementation principle of computed uses Vue’s responsive system, so to understand the implementation principle of computed, you need to first understand how Vue’s responsive system works.

Vue’s responsive system is implemented based on Object.defineProperty. Object.defineProperty is a method in ES5. When adding properties to an object, you can specify whether the property is writable, enumerable, and deletable. You can also specify getter and setter methods. The essence of Vue's responsive system is to use the getter and setter methods in the Object.defineProperty method to notify all dependencies to update when the properties are modified.

In Vue, the data object data is processed into an Observer object, and getter and setter methods are added for each property in the data object. When the properties of the data object are accessed or modified, Vue will listen and respond by executing user-defined functions.

The implementation principle of the computed attribute is to make use of such attributes. When defining a computed property, Vue will listen for its dependencies, which is the data on which the computed properties depend. When the dependent data changes, the calculated property will be triggered to be recalculated and the results of the calculated property will be cached. This implementation of calculated properties can effectively avoid repeated calculations and improve the performance of Vue applications.

Optimized practical solution

Computed is a very important feature in Vue, which improves the performance of applications. However, there are still some problems and things that need attention during use. This section will discuss optimized practical solutions for computed.

1. Don’t abuse calculated properties

Computed is an extremely convenient way to calculate data, but it is not suitable for calculated properties in all cases. If you use calculated properties excessively, it may have a great impact on performance and even affect the speed of application running. Therefore, when the results of calculated attributes can be calculated through methods, watches, filters, etc., you should try to avoid using calculated attributes.

2. Reasonable use of caching

The advantage of computed is that it caches dependencies and avoids repeated calculations. This can greatly improve the performance of your application. However, not all computed properties should have caching enabled. For some calculations where responsive data has not changed, if caching is enabled, the calculation results will be inconsistent with the actual results. In this case, caching should be turned off and a recalculation forced.

3. Data Optimization

When using calculated properties to perform a large number of calculations, you need to consider the speed of calculation and the speed of response. In order to ensure calculation speed and response speed, data needs to be optimized. For example: reduce the amount of calculations required through paging, virtual scrolling, etc.; conduct necessary filtering and screening of data to filter out unnecessary data during calculations; for complex calculations, calculations can be put into the computer through workers, web workers, etc. Executed in a separate thread.

4. Batch update

When the responsive data changes, computed will be re-executed. If there are multiple computed at the same time, unnecessary calculation functions will appear. execution, resulting in inefficiency. To solve this problem, Vue provides a $nextTick function. It can combine many calculation re-execution operations into one operation and execute it on the next Tick, thereby achieving batch updates and further improving computing efficiency.

5. Lazy calculation

If the calculation of calculated properties takes a long time, you can consider using the "lazy calculation" method for calculated properties that do not need to be used immediately. Calculation operations are only performed when the computed properties are accessed, thus avoiding wasting computing resources.

Conclusion

computed is an important feature in Vue. It uses Vue's responsive system to implement automatic calculation and improves performance through the caching mechanism. When developing Vue applications, you should use computed reasonably, and you should also pay attention to the performance issues of computed properties. Through reasonable use of cache, batch updates, lazy calculation, etc., the performance and experience of Vue applications can be maximized.

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