C questions

State in React Native can be managed using the `useState` hook for functional components or `this.state` in class components. For more complex state management, you can use context API or state management libraries like Redux or MobX. State is used to store data that affects how the component renders and behaves.

In React Native, you can navigate between screens using navigation libraries like React Navigation or React Native Navigation. React Navigation provides components such as `Stack.Navigator`, `Tab.Navigator`, and `Drawer.Navigator` to handle different types of navigation. It allows for the easy setup of stack, tab, and drawer navigators to manage screen transitions.

Props (short for properties) are read-only attributes passed to React components. They allow you to pass data and event handlers to child components, enabling component reusability. For example, if you have a `<Button>` component, you can pass text and an onPress handler as props to customize its behavior and appearance.

In React Native, permissions are handled using the `react-native-permissions` library or platform-specific APIs. The library provides a unified API for requesting and checking permissions on both iOS and Android. For example, you can request camera permission by calling `Permissions.request('camera')` and handle the response accordingly.

`react-native-svg` is a library that provides SVG support in React Native applications. It allows you to use SVG elements and attributes to create vector graphics, which are scalable and resolution-independent. This library is useful for displaying custom icons, charts, and other graphics that require high-quality rendering.

`useEffect` is used to perform side effects in functional components, such as data fetching, subscriptions, or manually changing the DOM. It runs after the render is committed to the screen. By specifying dependencies, you can control when the effect runs. For example, fetching data from an API when a component mounts.

The Context API in React Native allows you to pass data through the component tree without having to pass props manually at every level. You create a Context object using `React.createContext`, and then use `Provider` and `Consumer` components to manage and access the context data. This is useful for global state management and theme handling.

`React Native Navigation` is a library developed by Wix that provides a navigation solution with native performance and behavior. Unlike React Navigation, which is JavaScript-based, React Native Navigation uses native components for navigation, offering smoother and more performant transitions and interactions. It supports stack, tab, and drawer navigation with extensive customization options.

Vue components are reusable building blocks in a Vue application. Each component encapsulates its own template, logic, and styles, making it a self-contained unit of code. Components can be nested within other components to create complex UIs. This modular approach promotes code reusability, maintainability, and organization, allowing developers to manage and scale their applications more effectively.

The Vue instance is the core of every Vue.js application. It is created using the `Vue` constructor and serves as the root of a Vue application. The Vue instance connects the application to the DOM and provides various options and lifecycle hooks for managing the application's behavior. By initializing a Vue instance with options such as `data`, `methods`, and `mounted`, developers can define the application's state, methods, and lifecycle events.

Vue Router is the official routing library for Vue.js, allowing developers to implement navigation and routing within Vue applications. It enables the creation of single-page applications with dynamic views based on the URL. Vue Router provides features such as nested routes, route guards, and programmatic navigation, which help manage the navigation and rendering of different components based on the application's state or URL.

Vue.js handles conditional rendering through directives such as `v-if`, `v-else-if`, and `v-else`. These directives allow developers to control the visibility of elements based on a condition. When the condition specified in `v-if` evaluates to `true`, the element is rendered; otherwise, it is removed from the DOM. Vue also provides `v-show` for simpler conditional rendering that toggles the `display` CSS property without removing the element from the DOM.

To define a custom directive in Vue.js, you use the `Vue.directive` method. A custom directive allows you to create reusable, low-level behavior that can be applied to DOM elements. You can specify hooks such as `bind`, `inserted`, and `update` to manage the directive's behavior during various stages of the element's lifecycle. For example, a custom directive could handle custom formatting or event binding. Directives are useful for encapsulating complex or reusable DOM manipulations that are not easily covered by existing Vue directives.

Vue.js dynamic components allow you to switch between different components dynamically based on conditions. This is achieved using the `component` element along with the `:is` attribute, which can take a component name or component definition. For example, `<component :is='currentComponent'></component>` will render the component specified by `currentComponent`. Dynamic components are useful for scenarios where you need to render different components based on user interactions or application state without having to manage multiple static components.

Vue directives are special tokens in the markup that tell the Vue.js library to do something with the DOM. Directives are prefixed with `v-`, such as `v-bind` and `v-model`. They provide functionality for data binding, event handling, and conditional rendering. For example, `v-bind` can be used to dynamically bind an attribute to a component's data, while `v-if` can conditionally render elements based on a boolean expression.

Vue.js lifecycle hooks are methods that allow developers to execute code at specific stages of a component's lifecycle. These hooks include `created`, `mounted`, `updated`, and `destroyed`, among others. Each hook corresponds to a particular phase of the component's lifecycle, such as initialization, DOM insertion, and cleanup. By leveraging these hooks, developers can perform actions such as fetching data, setting up subscriptions, or cleaning up resources at appropriate times.

In Vue.js, `v-if` and `v-show` are both used for conditional rendering, but they work differently. `v-if` adds or removes elements from the DOM based on the condition, making it suitable for cases where elements are toggled rarely. In contrast, `v-show` toggles the `display` CSS property of the element, keeping it in the DOM but hiding it from view. `v-show` is more performant for frequently toggled elements since it avoids the cost of re-rendering, while `v-if` is more efficient for infrequent toggling.

Vue.js slots are a way to pass content into components, providing placeholders that can be filled with custom content. Slots allow for flexible and reusable components by enabling you to insert HTML or other components into a slot defined in a child component. Vue supports default slots, named slots, and scoped slots. Default slots are used for basic content insertion, named slots allow for multiple content areas, and scoped slots provide access to data within the slot's context, offering advanced customization options.

In Vue.js, a global event bus is a pattern used for cross-component communication, allowing different components to emit and listen to events outside of their hierarchical structure. An event bus is typically created by instantiating a new Vue instance and using it to manage event emission and listening. For example, `const eventBus = new Vue()` creates an event bus, and components can use `eventBus.$emit('eventName', data)` to emit events and `eventBus.$on('eventName', callback)` to listen for them. However, this pattern is less favored in modern Vue applications, with Vuex or the Composition API being recommended alternatives for managing state and communication.

Vue.js handles event handling using the `v-on` directive, which allows developers to listen for and respond to DOM events. By using `v-on` followed by the event name, such as `v-on:click`, you can bind event listeners to methods or inline expressions. Vue provides a shorthand `@` for `v-on`, making it easier to write event handlers. Event handling in Vue is straightforward and supports event modifiers for tasks like stopping event propagation or preventing default actions.

Vue.js uses a reactive data binding system to handle updates to the user interface automatically. When the state of a Vue instance or component changes, Vue’s reactivity system ensures that the changes are reflected in the DOM. This is achieved through a combination of getters, setters, and dependency tracking. Vue’s reactivity system leverages ES5 getters and setters to observe changes to data properties and trigger updates to the DOM as needed.

Vue.js mixins are a mechanism for reusing code across multiple components. A mixin is an object that contains properties, methods, and lifecycle hooks that can be shared among components. By defining a mixin, you can encapsulate reusable logic and then include it in any component that requires it. This helps reduce code duplication and keeps components clean. Mixins are particularly useful for sharing common functionality or behavior that is needed in several places within an application.

In Vue.js, a computed property is a property that is automatically recalculated based on reactive data dependencies. Computed properties are defined in the `computed` option of a Vue component and are used for performing calculations or transformations of data. Unlike methods, computed properties are cached based on their dependencies, meaning they are only recalculated when the dependent data changes. This makes computed properties efficient for scenarios where derived data needs to be computed from existing state.

In Vue.js, `refs` are used to access DOM elements or child components directly. By adding a `ref` attribute to an element or component, you create a reference that can be accessed via `this.$refs` in the Vue instance. This is useful for interacting with the DOM or child components imperatively, such as focusing an input element or calling methods on a child component. However, it is generally recommended to use Vue's declarative features whenever possible and resort to `refs` only when necessary.

Vue CLI is a command-line interface tool for scaffolding and managing Vue.js projects. It provides a powerful and extensible set of tools for creating new projects, managing dependencies, and running development servers. With Vue CLI, developers can quickly generate a new project with a standard configuration, integrate various plugins, and perform tasks such as building and deploying applications. It simplifies the setup process and offers a range of options for customizing and optimizing Vue projects.