Vue.js is a progressive JavaScript framework used for building user interfaces. It's designed to be incrementally adoptable and can easily integrate into existing projects.
Vue.js offers features like declarative rendering, component-based architecture, two-way data binding, directives, reactivity, virtual DOM, and templates.
The Virtual DOM is a lightweight in-memory representation of the actual DOM. Vue.js uses it to efficiently update the real DOM based on changes in the data model.
Directives are special HTML attributes that Vue.js provides to manipulate the DOM. Examples include 'v-bind', 'v-model', 'v-for', and 'v-if'.
Components in Vue.js are reusable, self-contained units of code that encapsulate HTML, CSS, and JavaScript logic. They promote reusability and maintainability.
Components can be created using the 'Vue.component()' method or by defining them as object literals using 'Vue.extend()'.
Data binding in Vue.js establishes a connection between the UI and the underlying data model, ensuring that changes in one are reflected in the other automatically.
Computed properties in Vue.js are functions that are cached based on their dependencies and are recalculated only when those dependencies change.
Vue.js lifecycle hooks are predefined methods that allow you to execute code at specific stages of a component's lifecycle, such as 'created', 'mounted', 'updated', and 'destroyed'.
Vue.js provides various techniques for input validation, including using built-in validators, custom validation methods, and third-party libraries like Vuelidate.
Vuex is a state management pattern and library for Vue.js applications. It helps manage application state in a centralized store, making state mutations predictable.
Vue.js offers two-way data binding and various directives like 'v-model' to easily bind form input fields to the underlying data model.
<template>
<div>
<input type="text" v-model="name">
<button @click="submitForm">Submit</button>
</div>
</template>
<script>
export default {
data() {
return {
name: ''
};
},
methods: {
submitForm() {
console.log('Form submitted with name:', this.name);
}
}
};
</script>
Single file components in Vue.js encapsulate a component's template, script, and styles in a single file with the '.vue' extension, promoting modularity and maintainability.
'v-if' conditionally renders elements based on a truthy value, while 'v-show' toggles the element's visibility based on a truthy value without altering the DOM structure.
Vue.js provides the 'vue-resource' and 'axios' libraries for making AJAX requests. Alternatively, you can use the native 'fetch' API.
Vue.js offers a built-in router called Vue Router, which enables navigation between different views in a Vue.js application using a client-side routing approach.
'watch' properties observe changes in data and execute custom logic in response, while 'computed' properties automatically recalculate based on their dependencies.
Vue.js provides the 'v-bind:class' and 'v-bind:style' directives for dynamically binding CSS classes and styles based on data or computed properties.
<template>
<div :class="{ active: isActive, 'text-danger': hasError }" :style="{ fontSize: fontSize + 'px' }">
Dynamic Class and Style Binding Example
</div>
</template>
<script>
export default {
data() {
return {
isActive: true,
hasError: false,
fontSize: 16
};
}
};
</script>
Vue.js allows you to handle DOM events using the 'v-on' directive, shorthand syntax '@', and methods defined in the component's 'methods' object.
Mixins in Vue.js are reusable code snippets that can be shared across multiple components to encapsulate common functionality.
Server-side rendering in Vue.js involves rendering Vue components on the server and sending the fully rendered HTML to the client, improving initial page load performance and SEO.
Performance optimization techniques in Vue.js:
The Vue CLI is a command-line interface tool used for scaffolding Vue.js projects, managing dependencies, and building production-ready applications.
Global state management in Vue.js can be achieved using event buses, props drilling, or a centralized Vue instance as a global event emitter.
Slots in Vue.js allow you to compose components by providing placeholders for markup or components to be injected from the parent component.
Scoped styles in Vue.js limit the scope of CSS to the current component, preventing styles from leaking into other components.
<template>
<div class="container">
<p class="text">Scoped Styles Example</p>
</div>
</template>
<style scoped>
.container {
background-color: #f0f0f0;
padding: 20px;
}
.text {
color: blue;
}
</style>In Vue.js, animations are handled using the '<transition>' component, which wraps elements and applies CSS transitions or animations when they are inserted, updated, or removed from the DOM, creating smooth and visually appealing effects.
Vue.js mixins are reusable code snippets that can be applied to multiple components to share common functionality. They are useful for code reuse and keeping components DRY (Don't Repeat Yourself).
Watchers in Vue.js are functions that watch for changes to a specific property and execute custom logic when the property changes. They are useful for performing asynchronous or expensive operations in response to data changes.
Reactivity in Vue.js refers to the ability of the framework to automatically update the DOM when data changes. Vue achieves reactivity through its reactive data model and dependency tracking system.
export default {
data() {
return {
message: 'Hello'
};
},
created() {
setTimeout(() => {
this.message = 'World'; // Triggers reactivity, updates DOM
}, 2000);
}
};
Route navigation guards in Vue.js allow you to control navigation behavior based on conditions like authentication status or data loading. You can use 'beforeEach', 'beforeResolve', and 'afterEach' hooks in Vue Router to implement guards, ensuring certain conditions are met before navigating to a route.
Scoped slots in Vue.js allow a child component to expose data or functionality to its parent component, enabling more flexible and reusable component composition.
<template>
<div>
<my-component>
<template v-slot:default="slotProps">
</template>
</my-component>
</div>
</template>
<script>
import MyComponent from './MyComponent.vue';
export default {
components: {
MyComponent
}
};
</script>
Render functions in Vue.js provide a programmatic way to generate and manipulate DOM elements using JavaScript instead of templates, offering more flexibility and control over the rendering process.
Error handling in Vue.js applications involves strategies like using try-catch blocks around critical code sections, implementing global error handlers with Vue's 'errorCaptured' lifecycle hook, or utilizing third-party error tracking services like Sentry or Bugsnag to monitor and debug errors occurring in production environments. Additionally, Vue.js offers error boundaries with components like '<ErrorBoundary>' in libraries like Vue 3 Error Boundary.
Vue.js directives are special tokens in the markup that tell the library to do something to a DOM element. For example, 'v-if', 'v-for', 'v-bind', and 'v-on' are commonly used directives.
<template>
<div>
<p v-if="show">This paragraph is rendered conditionally</p>
<button @click="toggle">Toggle Visibility</button>
</div>
</template>
<script>
export default {
data() {
return {
show: true
};
},
methods: {
toggle() {
this.show = !this.show;
}
}
};
</script>
Vue.js provides various ways to handle component communication, including props, custom events, event buses, Vuex for state management, and the provide/inject API for cross-component communication.
The 'key' attribute is used in Vue.js to provide a unique identifier for each DOM element within a list, enabling Vue.js to efficiently update the DOM when the order of the list changes.
Vuex is a state management pattern and library for Vue.js applications. It's used to manage the application's state in a centralized store, making it easier to maintain and manage complex application state.
To optimize Vue.js apps for SEO, consider server-side rendering with Nuxt.js, adding meta tags and structured data, pre-rendering static pages, using History mode in Vue Router, and focusing on site speed, mobile-friendliness, and accessibility.
Vue.js filters allow you to apply formatting or transformation to data before rendering it in the template. They are useful for formatting dates, currency, or other types of data.
<template>
<div>
<p></p>
</div>
</template>
<script>
export default {
data() {
return {
message: 'hello world'
};
},
filters: {
capitalize(value) {
if (!value) return '';
value = value.toString();
return value.charAt(0).toUpperCase() + value.slice(1);
}
}
};
</script>
Mixins are reusable code snippets that can be applied to multiple components to share common functionality, while components are self-contained units of UI, including HTML, CSS, and JavaScript logic.
Vue.js provides built-in features for form validation, including input validation directives like 'v-model', custom validation methods, and third-party libraries like Vuelidate or VeeValidate.
The 'transition' component in Vue.js is used to apply CSS transitions or animations when elements are inserted, updated, or removed from the DOM, providing a smooth user experience.
Dynamic components in Vue.js allow you to dynamically switch between different components at runtime based on a condition or user interaction, enhancing flexibility and code reusability.
HTTP interceptors in Vue.js can be implemented using Axios interceptors or plugins to intercept and modify HTTP requests and responses globally or for specific API calls.
// Axios HTTP interceptor example
import axios from 'axios';
axios.interceptors.request.use(
config => {
// Modify request config here
return config;
},
error => {
return Promise.reject(error);
}
);
Vue.js mixins are reusable code snippets that can be applied to multiple components to share common functionality. They should be used cautiously to avoid conflicts and maintain component clarity.
Server-side rendering (SSR) in Vue.js involves rendering Vue components on the server and sending the fully rendered HTML to the client, improving performance and SEO.
// Server-side rendering with Vue.js example
import Vue from 'vue';
import App from './App.vue';
import { createRenderer } from 'vue-server-renderer';
const renderer = createRenderer();
renderer.renderToString(App, (err, html) => {
if (err) throw err;
console.log(html); // Rendered HTML
});
Global event buses in Vue.js can be implemented using a Vue instance as an event bus or by using third-party event bus libraries like 'mitt' or 'Vue EventBus'.
Dynamic directives in Vue.js allow you to dynamically bind or unbind directives to elements based on conditions or user interactions, providing more flexibility in component behavior.
Slot-scope in Vue.js allows a parent component to pass data or functionality to a slot in a child component, enabling more powerful and flexible component composition and customization.