Vue 3 Code Breakdown

Vue 3 Code Explanation

Below is a succinct explanation of a basic Vue 3 code snippet. This breakdown will help you understand the core concepts and structure of a typical Vue 3 application.

Code Snippet

<template>
  <div id="app">
    <h1>{{ message }}</h1>
    <button @click="reverseMessage">Reverse Message</button>
  </div>
</template>

<script>
import { ref } from 'vue';

export default {
  name: 'App',
  setup() {
    // Reactive state
    const message = ref('Hello Vue 3');

    // Methods
    const reverseMessage = () => {
      message.value = message.value.split('').reverse().join('');
    };

    // Expose to template
    return {
      message,
      reverseMessage
    };
  }
};
</script>

<style scoped>
#app {
  font-family: Avenir, Helvetica, Arial, sans-serif;
  text-align: center;
  margin-top: 60px;
}
button {
  margin-top: 20px;
}
</style>

Sections Breakdown

1. Template Section

The <template> section is where you define the HTML structure of your component. Vue provides a special syntax for binding data and handling events.

<template>
  <div id="app">
    <h1>{{ message }}</h1>
    <button @click="reverseMessage">Reverse Message</button>
  </div>
</template>

• <div id="app">: The root element of the component.
• <h1>{{ message }}</h1>: Displays the message variable using Vue's mustache syntax for data binding.
• <button @click="reverseMessage">: An event listener that binds a click event to the reverseMessage method.

2. Script Section

The <script> section includes the JavaScript logic of your component.

<script>
import { ref } from 'vue';

export default {
  name: 'App',
  setup() {
    // Reactive state
    const message = ref('Hello Vue 3');

    // Methods
    const reverseMessage = () => {
      message.value = message.value.split('').reverse().join('');
    };

    // Expose to template
    return {
      message,
      reverseMessage
    };
  }
};
</script>

• import { ref } from 'vue';: Imports the ref function from Vue, which is used to create reactive state variables.

• name: 'App': Defines the name of the component.

• setup(): The setup function is the entry point for using the Composition API in Vue 3.

  • Reactive state:
    • const message = ref('Hello Vue 3');: Creates a reactive state variable message initialized with "Hello Vue 3".
  • Methods:
    • const reverseMessage = () => { ... }: Defines a method reverseMessage that reverses the string stored in message.
  • Expose to template:
    • return { message, reverseMessage };: Returns the message and reverseMessage to be accessible in the template.

3. Style Section

The <style> section contains the CSS styles that apply specifically to this component.

<style scoped>
#app {
  font-family: Avenir, Helvetica, Arial, sans-serif;
  text-align: center;
  margin-top: 60px;
}
button {
  margin-top: 20px;
}
</style>

• <style scoped>: Ensures the styles are scoped to this component only.
• CSS rules: Styles for the #app id and button element to control their appearance.

Conclusion

The above snippet demonstrates a basic example of a Vue 3 component using the Composition API. It includes data binding, event handling, and scoped styles, which are core concepts in building Vue 3 applications.

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