**Course Title:** Mastering Vue.js: Building Modern Web Applications **Section Title:** Vue Components and Props **Topic:** Creating and using components ### Creating and Using Components In the previous topic, we introduced the component-based architecture of Vue.js. Now, let's dive deeper into creating and using components to build modular, reusable, and maintainable web applications. #### What are Components? In Vue.js, a component is a self-contained piece of code that represents a UI element. It has its own template, styles, and logic. Components can be reused throughout an application, making it easier to develop and maintain complex UIs. #### Creating a Component To create a Vue component, you need to define a `VueComponent` object. The basic structure of a Vue component is as follows: ```html // MyComponent.vue <template> <!-- template here --> </template> <script> export default { // component logic here } </script> <style> /* styles here */ </style> ``` In this example, we define a component named `MyComponent` with a template, script, and style section. #### Registering and Using Components To use a component in a Vue application, you need to register it first. There are two ways to register a component: global registration and local registration. **Global Registration** You can register a component globally using the `Vue.component()` method. ```javascript // main.js import Vue from 'vue' import App from './App.vue' import MyComponent from './MyComponent.vue' Vue.component('my-component', MyComponent) new Vue({ render: h => h(App) }).$mount('#app') ``` Now you can use the `MyComponent` component anywhere in your application. **Local Registration** You can also register a component locally within a Vue component scope. ```html // App.vue <template> <div> <my-component /> </div> </template> <script> import MyComponent from './MyComponent.vue' export default { components: { MyComponent } } </script> ``` In this example, we import the `MyComponent` component and register it locally within the `App` component scope. #### Key Concepts * **Component Name**: The name of a component should be in kebab-case (e.g., `my-component`) and should be unique within a Vue application. * **Component Instance**: When a component is instantiated, a new Vue instance is created, and the component's template, scripts, and styles are applied to it. * **Component Tree**: Vue components can be nested to create a component tree, making it easier to manage complex UIs. #### Practical Takeaways * Use components to break down a complex UI into smaller, reusable pieces. * Use global registration for frequently used components, and local registration for components specific to a particular part of the application. * Use kebab-case for component names to ensure consistency and avoid conflicts. ### Example Use Case Suppose we want to build a todo list application using Vue components. We can create a `TodoItem` component to represent each todo item and a `TodoList` component to render the list of todo items. ```html // TodoItem.vue <template> <div> {{ todo.text }} </div> </template> <script> export default { props: { todo: Object } } </script> ``` ```html // TodoList.vue <template> <div> <todo-item v-for="todo in todos" :key="todo.id" :todo="todo" /> </div> </template> <script> import TodoItem from './TodoItem.vue' export default { components: { TodoItem }, data() { return { todos: [ { id: 1, text: 'Buy milk' }, { id: 2, text: 'Walk the dog' }, { id: 3, text: 'Do laundry' } ] } } } </script> ``` In this example, we create a `TodoItem` component to represent each todo item and a `TodoList` component to render the list of todo items using the `TodoItem` component. ### What's Next? In the next topic, we'll discuss how to pass data from a parent component to a child component using props. [Learn more about props in Vue.js](https://vuejs.org/v2/guide/components-props.html). Do you have any questions or need help with this topic?