Which is better to use v-if or v-show in vue?

In recent years, the application of MVVM framework in front-end development has become more and more popular, especially Vue.js, which is widely used. Vue.js is a lightweight MVVM framework for building pages quickly and efficiently. In Vue.js, v-if and v-show are two commonly used instructions. They can both implement conditional rendering, but the difference is that the implementation mechanisms and usage scenarios of v-if and v-show are slightly different. This article will discuss which one is better, v-if or v-show, in Vue.js.

1. The concepts and usage of v-if and v-show

In layman’s terms, v-if and v-show are instructions to implement conditional rendering. But their usage and implementation mechanisms are slightly different.

The usage of v-if is to add the v-if instruction to a DOM element. When certain conditions are met, the DOM element will be rendered on the page. For example:

<div v-if="flag">渲染的内容</div>

When the flag is true, this div element will be rendered, otherwise it will not be rendered. It should be noted that when the flag is false, the actual HTML code of this DOM element will not be loaded into the page.

The usage of v-show is similar. It also adds the v-show instruction to a DOM element, but the implementation mechanism of v-show is to control the CSS style attributes of the DOM element:

<div v-show="flag">渲染的内容</div>

When When the flag is true, the display value in the CSS style attribute of the div element is set to "block", that is, it is displayed; when the flag is false, the display value in the CSS style attribute is set to "none", that is, the The element is hidden.

2. Comparison between v-if and v-show

Theoretically, the implementation mechanism of v-if is more flexible because the v-if instruction controls It is whether the DOM element itself is rendered. When the conditions are not met, the event handling function and sub-component in the DOM element will be destroyed, and the memory and other resources related to it will be released. Therefore, when you need to frequently switch the display state of DOM elements, using v-if will be more efficient.

The advantage of v-show is that it controls display and hiding based on CSS styles. Regardless of whether the conditions are met or not, the DOM element always exists on the page. Therefore, when the display state of DOM elements needs to be frequently switched, using v-show is slightly inferior to v-if in terms of performance, but for those DOM elements that are frequently displayed and hidden on the page, v-show may be more consistent. Actual demand.

3. Summary

To sum up, v-if and v-show in Vue.js have their own advantages. v-if is suitable for those who need to control the display and hiding of DOM elements efficiently, while v-show is suitable for those DOM elements that need to be displayed or hidden frequently, or that need to respond more quickly when the page size or status changes. Therefore, in actual development, we should choose to use v-if and v-show flexibly according to specific scenarios and actual needs.

In short, in Vue.js, v-if and v-show are widely used and have similar functions and effects, but the implementation mechanisms are slightly different and need to be used flexibly according to actual needs.

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