vue displays different elements based on different selections

With the continuous development of the Internet, websites and applications pay more and more attention to user experience. One important aspect is making the user interface more personal and flexible. In this case, dynamic rendering of elements becomes very important. Vue is a popular JavaScript framework that makes it very easy to dynamically render elements. In this article, we will learn how to use Vue to display different elements based on different selections.

Vue Basics

Before we start, we first need to understand some basic knowledge of Vue. What is Vue? Vue is a modern JavaScript framework for building user interfaces. At its core is a reactive system that makes it easy to bind data to the DOM. Vue provides many instructions, components and life cycle functions to help us manage and operate the DOM more easily.

In Vue applications, data and views are bound to each other. When the data changes, the view changes accordingly. This responsive system makes it very easy to dynamically render elements. A directive in Vue is a special HTML attribute that instructs Vue how it should handle DOM elements.

v-if directive

The v-if directive is one of the most commonly used directives in Vue. It is used to dynamically render elements based on conditions. The syntax of the v-if directive is as follows:

<template>
  <div>
    <div v-if="condition1">Content 1</div>
    <div v-if="condition2">Content 2</div>
  </div>
</template>

In the above code, we use the v-if directive to dynamically render different content based on different conditions. When condition1 is true, Content 1 will be displayed; when condition2 is true, Content 2 will be displayed. If both condition1 and condition2 are false, then neither div element will be displayed.

Notes on the v-if directive

v-if is a lazy directive. This means that if the condition is false, the element will not be rendered into the DOM. This can improve performance if you have a large number of elements that need to be rendered dynamically in your Vue application.

Another thing to note is that v-if can be used in conjunction with v-else. v-else is a subsidiary instruction of v-if, which is used to render another element while one element is rendered by the v-if instruction. The v-else directive must be written after the v-if directive and at the same level.

<template>
  <div>
    <div v-if="condition1">Content 1</div>
    <div v-else-if="condition2">Content 2</div>
    <div v-else>Content 3</div>
  </div>
</template>

In the above code, when condition1 is true, Content 1 will be displayed; when condition1 is false and condition2 is true, Content 2 will be displayed; when condition1 and condition2 are both false, Content 2 will be displayed. Content 3.

v-show directive

Another way to dynamically render elements is to use the v-show directive. The v-show directive is similar to the v-if directive, but it does not dynamically render elements by controlling whether the element is rendered in the DOM. In contrast, v-show achieves control by changing the element's CSS property display.

The syntax of the v-show directive is as follows:

<template>
  <div>
    <div v-show="condition1">Content 1</div>
    <div v-show="condition2">Content 2</div>
  </div>
</template>

If condition1 is true, then the first div element will be displayed, and the second div element will be hidden. If condition2 is true, then the second div element will be displayed and the first div element will be hidden. If both condition1 and condition2 are false, both div elements will be hidden.

Notes on the v-show directive

Unlike v-if, the v-show directive always renders the element into the DOM, but only controls the visibility of the element through the CSS attribute display. This means that if you have a large number of elements that need to be dynamically rendered in a Vue application, the v-show directive may affect performance.

Another thing to note is that the v-show directive is more suitable for elements that need to be switched frequently. Because v-show only controls the visibility of elements by changing CSS properties, this is faster than v-if. However, for elements that don't need to be switched frequently, v-if may be better because it can completely remove the element from the DOM, thus improving performance.

Summary

In this article, we learned how to use Vue to display different elements based on different selections. We learned about the v-if and v-show instructions and understood their differences and precautions. For Vue application developers, dynamically rendering elements is very important. By understanding the basics of Vue, we can easily implement dynamically rendered elements, thereby improving the user experience of our applications.

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