How does Vue optimize rendering performance and achieve high-efficiency refresh?

As a popular JavaScript framework, Vue is favored by more and more developers for its efficient data binding and component-based development model. However, in large-scale applications, due to the increase in data volume and the increase in component complexity, page rendering performance issues have become increasingly prominent.

How to optimize the performance of Vue to achieve efficient refresh? Here are some useful suggestions:

1. Reasonable use of v-if and v-show

Both v-if and v-show can be used to control whether a component or element Rendering, but there is a difference between the two: v-if dynamically adds or removes elements, and v-show dynamically switches the display and hiding of elements. In use, v-show is more lightweight than v-if, because the component will still be rendered, just hidden, while v-if needs to be rendered when the component needs it.

Therefore, when the amount of data is large, reasonable use of v-show can reduce the pressure of page rendering. In situations where components need to be switched frequently, using v-if would be more appropriate.

2. Avoid unnecessary computed properties and listeners

Vue's computed properties and listeners are very powerful and flexible and can respond to and process changes in data. However, if the dependency between computed properties and listeners is unreasonable, it can easily lead to performance problems. Therefore, we should try to avoid unnecessary computed properties and listeners.

A common scenario is: in a list, each item needs to calculate some complex properties, but the calculation results of many items are the same. If each entry is calculated individually, there will be double calculations, wasting performance.

In order to avoid this situation, you can convert calculated properties into methods and cache the calculation results to avoid repeated calculations.

3. Reasonable use of asynchronous components and dynamic components

Asynchronous components and dynamic components are very powerful features in Vue, which can improve application performance while achieving on-demand loading. Asynchronous components can delay the loading of components until the component is first rendered, while dynamic components can dynamically switch different components based on different data. Since both components can reduce the initialization time of page rendering, we should use them whenever possible.

4. Reasonable use of v-for and key attributes

v-for is an instruction used in Vue to loop through the rendering list, but if there is no loop for each list when rendering the list, Adding key attributes to child elements will cause rendering performance problems. Because when Vue updates the DOM, it needs to match old nodes and new nodes through key attributes to determine which nodes need to be updated, deleted or added. If there is no key attribute, you can only use index to match the nodes, so you need to re- Calculating the location of nodes wastes performance.

5. Reasonable use of v-cloak and v-once

The v-cloak directive can hide the page template before the Vue instance is loaded, and then display it after the instance is loaded. This can avoid the effect of the page passing by and improve the user experience.

The v-once directive can render an element or component only once, avoiding unnecessary repeated rendering.

Summary

Vue is a very excellent framework, but in order for it to take full advantage of its efficient features, its rendering performance must be optimized. The above are some practical optimization suggestions. I believe that as long as you follow these principles, Vue can run more smoothly and bring a better user experience.

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