How to use responsive data to update DOM in Vue

As one of the modern front-end frameworks, Vue.js provides a wealth of tools and syntax to help developers build responsive applications. In Vue, reactive data is very important. They allow us to update the DOM when the data changes without having to manually manipulate the DOM. Next, we will learn about some key concepts and code syntax in Vue to help us better update the DOM with responsive data.

1. Responsive data

Responsive data in Vue means that when the data changes, the DOM will automatically update to reflect these changes. Data binding in Vue is one-way, that is, once the data is bound to the view, the view will automatically update when the data changes. We can use the v-bind directive to bind data to HTML element attributes and the {{...}} expression to bind data to HTML element content.

For example, the following code demonstrates how to bind a variable message to the content of a p element:

<template>
  <div>
    <p>{{ message }}</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      message: 'Hello World'
    }
  }
}
</script>

When we update the message variable, the content of the p element will also be automatically updated. .

2. computed attribute

Sometimes we need to calculate a new value based on existing data and use it to update the DOM. Vue provides computed attributes to solve this problem. The computed attribute is a data-based calculated attribute. Its core idea is to allow the system to automatically monitor dependent data changes and automatically update the computed value.

For example, the following code demonstrates how to use the computed attribute to calculate the length of a name and render it into the DOM:

<template>
  <div>
    <p>{{ nameLength }}</p>
  </div>
</template>

<script>
  export default {
    data() {
      return {
        name: 'Vue.js'
      }
    },
    computed: {
      nameLength() {
        return this.name.length
      }
    }
  }
</script>

When we change the name value, the computed attribute will automatically update , and renders its new value into the DOM.

3. watch attribute

Sometimes we need to perform some specific operations when the data changes. Vue provides the watch attribute to solve this problem. The watch attribute can monitor data changes and perform specified operations when the data changes. The watch attribute can also be used to handle asynchronous operations, such as getting data from the server and rendering it into the DOM.

For example, the following code demonstrates how to use the watch attribute to perform an action when the variable value changes:

<template>
  <div>
    <input v-model="message" />
  </div>
</template>

<script>
export default {
  data() {
    return {
      message: 'Hello World'
    }
  },
  watch: {
    message(newValue, oldValue) {
      console.log('New value: ' + newValue + ', Old value: ' + oldValue)
    }
  }
}
</script>

When we enter different values ​​​​in the input box, the watch attribute will Automatically updates and logs new and old values ​​in the console.

4. Vue.js framework

Vue.js is a lightweight front-end framework. Its core idea is to separate the application state from the user interface. .

Vue.js organizes UI through components. Components can be nested and compounded. Each component has its own state and behavior.

Vue.js uses virtual DOM technology to improve the efficiency of page rendering. When the data changes, Vue.js will automatically re-render the virtual DOM and compare it with the old virtual DOM, thereby reducing the DOM The number of operations improves page performance.

Vue.js also provides some auxiliary tools and plug-ins, such as Vue Router and Vuex, which can help developers build more complex applications.

In general, the responsive data of Vue.js realizes automatic synchronization of data and views, greatly improving the efficiency and user experience of front-end development. We only need to pay attention to the changes in the data without having to manually manipulate the DOM. In actual projects, you need to flexibly apply the technology and syntax provided by Vue.js to build high-quality responsive applications.

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