Tips for using v-show and v-if to control the display and hiding of elements in Vue

Controlling the display and hiding of elements in Vue is a very common requirement, and v-show and v-if are two commonly used instructions in Vue to achieve this function. This article will introduce how to use these two instructions to control the display and hiding of elements, and discuss how to choose which instruction to use in actual development.

1. Basic usage of v-show

In Vue, you can use the v-show directive to control the display and hiding of elements. The usage of v-show is very simple. You only need to add the v-show directive to the element that needs to be controlled to be displayed and hidden, and bind it to a Boolean value. For example, use the following code in the template:

<div v-show="show">
  我是要显示的元素
</div>

Among them, show is a Boolean type variable. By changing the value of the variable, you can display and hide elements.

The characteristic of v-show is that it does not modify the existence or absence of DOM elements, but only displays and hides elements through CSS style control. Therefore, when the page loads, even if the element is hidden, it will still be loaded into the DOM and will not affect the page loading speed.

2. Basic usage of v-if

Different from v-show, the v-if instruction will determine whether to insert elements into the DOM based on the Boolean type variable value. When the variable value is true, the element will be inserted into the DOM; when the variable value is false, the element will not be inserted into the DOM. Therefore, v-if saves DOM resources more than v-show, but it also affects page loading speed.

The code for using the v-if directive in the template is as follows:

<div v-if="show">
  我是要显示的元素
</div>

Similarly, here, show is a Boolean type variable.

3. Choice between v-show and v-if

In actual development, we should choose to use v-show or v-if according to different scenarios.

1. If you need to frequently switch the display and hidden state of elements, you should use v-show. Because v-show only displays and hides elements by controlling CSS styles and does not reconstruct the DOM, switching the state of elements is very fast.
2. If an element will only appear once in the page or will only appear under certain conditions, using v-if can give you more control over the loading of the DOM. Because the characteristic of v-if is to insert an element into the DOM only when the condition is met, it can avoid wasting unnecessary DOM resources when the element does not need to be displayed.
3. If you need to quickly display all elements when the page loads, you should use v-show. In the scenario of using v-if, since the element will only be inserted into the DOM when the condition is met, the page may be blank for a period of time. Using v-show can quickly display all elements when the page loads.

4. Summary

v-show and v-if are common instructions in Vue for controlling the display and hiding of elements. Through the introduction of this article, you can find that each of these two instructions has its own advantages and disadvantages. In actual development, we should choose to use different instructions according to different scenarios to achieve optimal results.

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