Changes in Vue3 compared to Vue2: richer built-in instructions

Changes in Vue3 compared to Vue2: Richer built-in instructions

As time goes by, Vue.js, as a popular JavaScript framework, continues to be upgraded and improved. Vue3 is the latest version of Vue.js, which brings many important changes and upgrades compared to Vue2. One of the most significant changes is the richness of built-in commands. In this article, we will explore some changes in built-in directives in Vue3 compared to Vue2, and provide some code examples to illustrate these changes.

In Vue2, the built-in instructions we are familiar with mainly include: v-if, v-for, v-bind, v-on, etc. These instructions provide us with rich functions to handle common front-end development tasks such as data binding, conditional rendering, and loop rendering. However, in Vue3, these original built-in instructions have been improved and supplemented with some new built-in instructions.

First, let us start with a simple example to understand the improved built-in instructions in Vue3. Suppose we have a simple Vue application that contains a button that displays a tooltip when the button is clicked. In Vue2, we will use the v-if directive to implement this function. The sample code is as follows:

<template>
  <div>
    <button v-if="showDialog" @click="showDialog = false">点击显示提示框</button>
    <div v-else>
      <div class="dialog">
        <p>这是一个提示框！</p>
        <button @click="showDialog = true">关闭</button>
      </div>
    </div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      showDialog: false
    };
  }
};
</script>

In the above code, we use the v-if instruction to control the display and hiding of buttons and prompt boxes based on the value of showDialog. When showDialog is true, the button will be hidden and the prompt box will be displayed; when showDialog is false, the button will be displayed and the prompt box will be hidden. This is a common use of conditional rendering in Vue2.

However, in Vue3, we can use the new built-in instruction v-show to achieve the same functionality. The v-show directive has the same function as the v-if directive. They both control the display and hiding of elements based on the value of the expression. The difference is that v-show does not add or remove elements in the DOM, but controls the display and hiding by changing the CSS properties of the elements. The following is a code example of the same function rewritten using v-show:

<template>
  <div>
    <button v-show="showDialog" @click="showDialog = false">点击显示提示框</button>
    <div v-show="!showDialog">
      <div class="dialog">
        <p>这是一个提示框！</p>
        <button @click="showDialog = true">关闭</button>
      </div>
    </div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      showDialog: false
    };
  }
};
</script>

Through the above code example, we can see that we can use the v-show directive to replace the v-if directive to achieve the same function . In actual development, according to specific requirements and scenarios, we can choose to use v-if or v-show to achieve our needs.

In addition to v-show, Vue3 also introduces some new built-in instructions, such as v-model, v-bind, v-on, etc. These directives also exist in Vue2, but have been improved and enhanced in Vue3. Here is a simple example using the v-model directive:

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

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

In the above code example, we used the v-model directive to implement two-way data binding. When the user enters text in the input box, the v-model instruction will bind the value entered by the user to the message attribute in data. At the same time, when the message attribute in data changes, the text in the input box will also change accordingly. renew. The v-model directive makes the implementation of two-way data binding more concise and intuitive.

In addition to new instructions, Vue3 has also improved and enhanced some original instructions. For example, in Vue3, the v-bind directive can bind multiple property values ​​at the same time, as shown below:

<template>
  <div>
    <a v-bind="{ href: url, target: '_blank' }">点击打开链接</a>
  </div>
</template>

<script>
export default {
  data() {
    return {
      url: 'https://www.example.com'
    };
  }
};
</script>

In the above code example, we used an object to specify multiple properties to be bound. value. Pass the v-bind directive with an object as a parameter, and each property of the object will be parsed into a bound property.

To summarize, Vue3 brings many changes and improvements in built-in instructions. By introducing new instructions and improving the functionality of original instructions, Vue3 provides more options and a more flexible way to meet the needs of front-end development. By using new instructions and rewriting the sample code, we can have a clearer understanding of Vue3's changes in built-in instructions, and apply these changes in actual projects to improve development efficiency and code quality.

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