vue show hide command

Vue.js is a popular JavaScript framework. Its convenient template syntax and powerful directives make it the first choice for many developers. Among them, directives are a powerful tool used in Vue templates. They can be used to extend HTML elements and DOM operations. This article will introduce a common instruction in Vue.js - v-show, which can control the display and hiding of elements in the DOM.

1. Introduction to the v-show instruction

v-show is an instruction provided by Vue.js, which can determine the display and hiding of elements based on the value of an expression. When the expression evaluates to true, the element is displayed; otherwise, the element is hidden. Unlike the v-if directive, the v-show directive does not change the structure of the DOM, but only changes the style of the element.

The basic syntax of the v-show instruction is as follows:

Among them, element represents the HTML element to be bound to the instruction, and expression represents the expression to be bound to the element. When expression When the value of is true, the element will be displayed; otherwise, the element will be hidden.

2. How to use the v-show instruction

Let’s look at an example below, using the v-show instruction to control the display and hiding of a div element:

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In In this example, we use the v-show directive to bind a div element to the show variable. The value of the show variable can be defined in the Vue instance, for example:

var app = new Vue({
    el: '#app',
    data: {
        show: true
    }
})

In this Vue instance, the initial value of show is true, so the div element will always be displayed. Next, we can use the Vue.js method to change the value of the show variable to control the display and hiding of the element:

app.show = false;

When the value of the show variable becomes false, the div element will be Hidden, otherwise it will be shown again.

3. Notes on the v-show directive

1. The v-show directive only supports binding to DOM elements and cannot be bound to components.
2. The v-show directive does not affect the structure of the DOM, but controls the display and hiding of elements by modifying CSS properties. Therefore, when using the v-show directive, you need to ensure that the display attribute of the element has been defined, otherwise the directive will not work.
3. Although the v-show directive does not affect the structure of the DOM, it will still save the element in the DOM tree, and Vue.js will continue to process it as it updates the DOM. Therefore, using the v-show directive may increase the rendering burden and should be used with caution.
4. When using the v-show directive, it is recommended to use it only for elements that need to be switched frequently. For elements that are less modified, it is more appropriate to use the v-if directive.

In short, the v-show instruction is a powerful element display and hiding tool in Vue.js. It can help developers control the display and hiding of elements more conveniently, making the page interactive. More beautiful. During the development process, we should use this instruction reasonably according to the specific situation, follow the responsiveness principle of Vue.js, and improve the user experience and overall performance of the website.

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