面试题与答案

Svelte.js is a modern JavaScript framework that compiles components at build time, resulting in highly optimized and lightweight code for the browser.

The 'svelte:head' tag is used to dynamically update the document head with meta tags, title, and other head elements based on the component's state.

Conditional rendering in Svelte can be done using the 'if' and 'else' blocks. For example: {#if condition} ... {:else} ... {/if}

The 'bind:' directive in Svelte is used for two-way binding. It establishes a connection between a parent component's property and a child component's property, ensuring changes in one affect the other.

The 'on:' directive in Svelte is used to handle DOM events. For example: {on: {click: handleClick}}

Svelte allows you to include global CSS styles using the 'global' keyword. Styles defined with 'global' apply globally across all components.

You can conditionally apply CSS classes in Svelte using the 'class:' directive. For example: {class: active ? 'active' : 'inactive'}

Form submissions in Svelte can be handled using the 'on:submit' directive. You can prevent the default form behavior and implement your custom logic in the associated function.

In Svelte, the 'this' keyword refers to the instance of the current component. It can be used to access component methods, properties, and other features.

The 'bind:this' directive in Svelte is used to bind a DOM element to a variable, making it accessible in your component. Changes to the variable also reflect in the DOM element.

Svelte does not include built-in HTTP request functionality. Developers often use libraries like 'fetch' or 'axios' to handle HTTP requests in Svelte applications.

Reactivity in Svelte refers to the automatic updating of the DOM when the state of a variable changes. Svelte achieves this without the need for a virtual DOM.

Svelte compiles components to highly optimized JavaScript at build time, resulting in smaller bundle sizes and improved performance compared to traditional virtual DOM-based frameworks like React or Vue.

Svelte components have a simplified lifecycle compared to other frameworks. They do not have lifecycle methods like 'componentDidMount' or 'componentWillUnmount'. Instead, Svelte components have 'onMount' and 'onDestroy' lifecycle functions.

Stores in Svelte are reactive containers for state management. They allow sharing state between components and automatically update when the state changes.

Svelte has built-in support for animations. You can use the 'animate:' directive to create smooth transitions and animations between state changes in components.

Data can be passed from parent to child components in Svelte using props. The parent component can bind a variable to a child component property, ensuring updates are reflected in the child.

Svelte transitions enable smooth animations during element insertion, removal, or state changes. You can use 'in:' and 'out:' directives to specify transition effects.

The 'key' attribute in Svelte's each block is used to uniquely identify elements during iteration. It helps Svelte efficiently update the DOM when the list changes.

The 'context' API in Svelte allows components to communicate indirectly by sharing state with their descendants. It's useful for avoiding prop drilling.

The 'use:' directive in Svelte is used to apply actions to DOM elements. Actions are functions that can perform side effects, like animating or interacting with the DOM.

Svelte allows you to handle route parameters using the '$route' store. You can subscribe to changes in route parameters and update your component's state accordingly.

Svelte supports automatic code splitting, meaning that only the components used in a specific route or part of your application are included in the final bundle.

Side effects in Svelte can be handled using lifecycle functions like 'onMount' and 'onDestroy'. These functions are suitable for performing actions when a component is mounted or unmounted.

Slots in Svelte allow you to create reusable components with placeholders for content. They provide a way to pass content into a component from its parent.

The 'slot' attribute in Svelte is used to define named slots in a component. It allows the parent component to provide content for specific areas of the child component.

The 'await' block in Svelte is used for asynchronous logic. It allows you to await a Promise and handle the resolved value or catch errors within the template.

Reactive declarations in Svelte create reactive variables based on dependencies, while reactive statements directly execute code when dependencies change. Declarations use '$:' syntax, and statements use '{# ... }'.

The '$:`` syntax in Svelte is used for two-way binding. It allows you to create a reactive variable that is both readable and writable within a component.

State can be shared between sibling components in Svelte by lifting the state to a common parent and passing it down as props to both siblings.