Full analysis of the differences between Vue v-if and v-show and their application scenarios

The difference between Vue v-if and v-show and full analysis of application scenarios

In Vue.js, we often use v-if and v-show These two instructions control the display and hiding of elements based on conditions. Although they all have similar functions, there are some differences in how they are used and internally implemented. This article will analyze the difference between v-if and v-show in detail, and give some code examples for practical application scenarios.

v-if is a conditional rendering instruction that determines whether to render an element based on whether the specified expression is true or false. When the conditional expression is true, v-if will create the element and insert it into the DOM; when the condition is false, v-if will remove the element from the DOM. v-if will destroy and rebuild elements when switching, so it performs better in scenarios where switching frequency is low.

The following is an example of using v-if:

<div v-if="isShow">这是一个被v-if控制的元素</div>

In the above example, isShow is a Boolean type variable, which controls the display and hiding of this element. When isShow is true, this element will be rendered; when isShow is false, this element will be removed from the DOM.

In contrast, v-show is a conditional display instruction, which also determines whether to display an element based on the true or false of the specified expression. When the conditional expression is true, v-show will add the display: none style to the element to hide the element; when the condition is false, v-show will remove the style so that the element is displayed. When v-show is switched, it only switches the display attribute of the element, so the performance is better in scenarios with high switching frequency.

The following is an example of using v-show:

<div v-show="isShow">这是一个被v-show控制的元素</div>

In the above example, isShow is also a Boolean type variable, which controls the display and hiding of this element. When isShow is true, this element will be displayed in the normal way; when isShow is false, this element will be hidden.

So, how should v-if and v-show be chosen? Generally speaking, if there are frequent switching operations, we should give priority to using v-show because its switching performance is better. If there are fewer switching operations, or the content after switching is more complex, you can consider using v-if, because it can reduce unnecessary DOM operations and save memory.

In addition to the above basic usage, v-if and v-show can also be used with other instructions to add more flexibility and functionality. For example, we can combine v-if and v-for to render a list based on conditions:

<template v-if="isListVisible">
  <ul>
    <li v-for="item in itemList" :key="item.id">{{ item.name }}</li>
  </ul>
</template>

In the above example, when isListVisible is true, the list will be displayed and rendered based on the contents of itemList .

In summary, although v-if and v-show have similar functions, there are some differences in their usage and internal implementation. Choosing the right instructions based on the actual situation can improve performance and add more functionality. I hope this article will help you understand the differences and application scenarios of vue v-if and v-show.

Reference materials:

1. Vue.js official documentation: https://vuejs.org/
2. Vue.js Chinese documentation: https://cn. vuejs.org/

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