How does vue affect the real dom

Vue is a commonly used JavaScript framework that allows users to declaratively bind DOM elements to a responsive state, but they still need to be displayed in the HTML document. In this article, we will explore how Vue applies it to the real DOM.

Vue instance

First, we need to instantiate the Vue object and let it control the DOM elements in the page. We can use the Vue constructor to create a new Vue instance:

var vm = new Vue({
  el: '#app',
  data: {
    message: 'Hello, Vue!'
  }
})

In this example, we pass an object containing the el and data properties to the Vue instance. The el attribute indicates the DOM element to be controlled by the Vue instance, while the data attribute is the data attribute in the Vue object, usually used to declare reactive data.

Binding data

Vue instances allow data binding, which means that the attribute values ​​of DOM elements can be bound to the data attributes of Vue objects. This binding method can automatically update DOM elements, allowing the real DOM to dynamically update as the data attributes in the Vue object change.

We can use double curly brace syntax to bind data attributes in the Vue instance to DOM elements:

<div id="app">
  {{message}}
</div>

In this example, we use {{message}} to bind the data attributes in the Vue object The message in the data attribute is bound to the text content of the div element. This means that when the message attribute in the Vue instance changes, the text content in the div element will be updated accordingly.

Directives

Directives in Vue are special HTML attributes used to associate certain tasks with specified DOM elements. Vue provides a large number of instructions, including v-if, v-for, v-on and so on.

The v-if directive allows you to show or hide DOM elements based on conditional judgments in the Vue instance:

<div v-if="visible">This div will be displayed if visible is true.</div>

The v-for directive allows you to traverse arrays or objects in the Vue instance:

<ul>
  <li v-for="item in items">{{ item }}</li>
</ul>

In this example, the items attribute in the Vue instance is an array, the v-for directive traverses it and creates a li element in the DOM to display the value of the array element.

The v-on directive allows binding event listeners on DOM elements to trigger some JavaScript code when a specific event occurs:

<button v-on:click="counter++">You clicked me {{ counter }} times.</button>

In this example, we use the v-on directive to Bind a click event listener to the button element. When the user clicks the button, the counter property in the Vue instance is incremented by 1, and the button's text content is updated to show the number of clicks.

Summary

Vue is a very flexible and powerful framework that can easily apply JavaScript to real DOM operations. Vue instances can not only bind data, but also apply directives and event listeners to associate properties in Vue objects with specific DOM elements. Through these methods, we can apply Vue to the real DOM and ensure that the page dynamically responds to changes in data attributes in the Vue object.

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