Amdocs UI Frontend Developer Interview Questions and Answers

HTML5 is the latest version of the HTML standard, with new features for multimedia, graphics, and interactivity.

• Support for multimedia elements like <video> and <audio>

• Canvas and SVG for graphics rendering

• Improved form controls and validation

• Offline storage capabilities with Local Storage and IndexedDB

• Geolocation API for location-based services

• Web Workers for running scripts in background threads

CSS box model is a design concept that describes how elements are rendered on a web page.

• It consists of content, padding, border, and margin.

• Content is the actual element content.

• Padding is the space between the content and the border.

• Border is the line that surrounds the content and padding.

• Margin is the space between the border and the next element.

• The box model can be adjusted using CSS properties such as padding, b...read more

Prototype chaining is the mechanism by which objects inherit properties and methods from their prototype.

• Every object in JavaScript has a prototype property that refers to another object.

• If a property or method is not found on an object, JavaScript looks for it in the object's prototype chain.

• Prototype chaining can be used to create inheritance in JavaScript.

• Modifying the prototype of an object affects all objects that...read more

React is a JavaScript library for building user interfaces.

• Declarative approach to building UI

• Component-based architecture

• Virtual DOM for efficient updates

• JSX syntax for writing HTML in JavaScript

• One-way data binding

• Support for server-side rendering

• Large and active community

• Integration with other libraries and frameworks

Media elements are HTML tags used to embed media content like images, audio, video, etc. in a web page.

• Media elements include <img> for images, <audio> for audio files, and <video> for video files.

• They allow developers to easily integrate multimedia content into web pages.

• Attributes like src, alt, controls, autoplay, etc. can be used to customize the behavior of media elements.

Same Origin Policy is a security feature in web browsers that restricts web pages from making requests to a different domain.

• It prevents malicious scripts from accessing sensitive data from other websites

• It applies to all web content, including JavaScript, CSS, and images

• Cross-Origin Resource Sharing (CORS) is used to bypass the Same Origin Policy

• Example: A script from www.example.com cannot access data from www.anothe...read more

Redux is a predictable state container for JavaScript apps.

• Redux is a library for managing application state.

• It provides a single source of truth for the entire application state.

• Redux follows a unidirectional data flow pattern.

• Actions are dispatched to update the state, which triggers a re-render of the UI.

• Redux can be used with React, Angular, Vue, and other frameworks.

Thunk is a function that delays the evaluation of an expression.

• A thunk is a function that wraps an expression to delay its evaluation.

• It is commonly used in Redux to handle asynchronous actions.

• Thunks are used to dispatch actions that return a function instead of an object.

• Thunks can be used to handle side effects in React components.

Callbacks are functions passed as arguments to other functions and executed later.

• Callbacks are used for asynchronous programming.

• They allow a function to be called when an event occurs.

• They can be used to handle errors in asynchronous code.

• Examples include event listeners and setTimeout() function.

Promises are objects that represent the eventual completion or failure of an asynchronous operation.

• Promises have 3 states: pending, fulfilled, or rejected

• Pending is the initial state when a promise is created

• Fulfilled means the operation completed successfully

• Rejected means the operation failed

• Promises can be chained using .then() and .catch() methods

Callback hell refers to the difficulty of managing nested callbacks in asynchronous programming, leading to complex and unreadable code.

• Callback hell occurs when multiple nested callbacks are used, making code hard to read and maintain.

• Example: A series of asynchronous operations nested within each other, like fetching data, processing it, and then saving it.

• Using Promises can help flatten the structure and improve rea...read more

HTML provides various storage options like cookies, localStorage, and sessionStorage for web applications.

• Cookies: Small pieces of data stored on the client-side, sent with every HTTP request. Example: user preferences.

• localStorage: Stores data with no expiration time, accessible across sessions. Example: saving user settings.

• sessionStorage: Stores data for the duration of the page session, cleared when the tab is clos...read more

Worker threads allow for parallel execution of JavaScript code in the browser or Node.js environment.

• Worker threads can be used to perform CPU-intensive tasks without blocking the main thread.

• They can also be used to communicate between different scripts or modules.

• In Node.js, worker threads can be created using the 'worker_threads' module.

• In the browser, worker threads can be created using the 'Worker' constructor.

• Exa...read more

Create a simple input with a toggle to display input text when the toggle is ON.

• Use HTML for the input field and toggle switch.

• Utilize JavaScript to handle the toggle state and display logic.

• Example HTML: <input type='text' id='myInput'> <button id='toggle'>Toggle</button>

• Example JavaScript: Use an event listener on the toggle button to check its state.

• When ON, update a <div> with the input valu...read more