10+ UI Engineer Interview Questions and Answers

ES6 features like object destructuring, arrow functions, array methods

• Object destructuring allows for easy extraction of values from objects

• Arrow functions provide a concise syntax for writing functions

• Array.filter() allows for filtering of elements based on a condition

• Array.reduce() allows for reducing an array to a single value

• Array.indexOf() returns the index of the first occurrence of a specified element

Use CSS to set margin to auto for horizontal centering and text-align center for vertical centering.

• Set the parent div's display property to flex and justify-content to center

• Set the child div's margin property to auto

• Alternatively, set the parent div's text-align property to center and child div's display property to inline-block

Data can be transferred between components in Angular using @Input and @Output decorators.

• Use @Input decorator to pass data from parent to child component

• Use @Output decorator to emit events from child to parent component

• Use EventEmitter to emit custom events

• Use ViewChild to access child component's properties and methods

Var, let, const are used to declare variables in JavaScript. 'use strict' enables strict mode.

• Var is function-scoped and can be redeclared. Let and const are block-scoped and cannot be redeclared.

• Let allows reassignment while const does not.

• 'use strict' enables strict mode which enforces stricter rules and better error handling.

• Example: var x = 10; let y = 20; const z = 30;

• Example: 'use strict';

async/await in script tag is used to load external scripts asynchronously without blocking the page.

• async/await allows scripts to be loaded asynchronously without blocking the page

• It is useful for loading external scripts that may take time to load

• It improves page performance by not blocking the rendering of the page

• It is supported in modern browsers

CSS Box model is a design concept that describes how elements are displayed on a webpage.

• Every HTML element is a rectangular box

• The box has content, padding, border, and margin

• Width and height of the box are determined by content, padding, and border

• Margin is the space outside the border

• Box-sizing property can be used to change the box model

A B testing in design is a method of comparing two versions of a webpage or app to determine which one performs better.

• Involves creating two versions (A and B) with one differing element

• Randomly showing each version to users

• Analyzing user behavior and performance metrics to determine the better version

• Commonly used in web design, marketing campaigns, and user experience testing

A closure in JavaScript is a function that retains access to variables from its parent scope even after the parent function has finished executing.

• A closure allows a function to access and manipulate variables from its outer scope.

• Closures are created whenever a function is defined within another function.

• Example: function outerFunction() { let outerVar = 'I am outer'; return function innerFunction() { console.log(outerVar); }; }

Mixins in Less are reusable code blocks that can be included in other style rules.

• Mixins are defined using the .mixin() function in Less.

• They can be included in other style rules using the .mixinName(); syntax.

• Mixins can take parameters and return values, allowing for dynamic styling.

• Example: .border-radius(@radius) { border-radius: @radius; }

• Example usage: .myElement { .border-radius(5px); }

User persona is a fictional representation of a target user group based on research and data.

• User persona helps in understanding the needs, behaviors, and goals of the target audience.

• It includes demographic information, preferences, pain points, and motivations.

• Example: A user persona for an e-commerce website might be 'Sara, a 30-year-old working professional who values convenience and quality.'

JavaScript is a programming language commonly used for creating interactive effects within web browsers.

• JavaScript is a high-level, interpreted programming language.

• It is used to make web pages interactive and dynamic.

• JavaScript can be used for client-side and server-side development.

• Commonly used frameworks/libraries include React, Angular, and Vue.

• Example: document.getElementById('demo').innerHTML = 'Hello, World!';

Create a user-friendly outlook interface for displaying emails.

• Implement a clean and organized layout with easy navigation.

• Include features such as search functionality, filters, and sorting options.

• Display email previews with sender information, subject line, and timestamp.

• Allow users to mark emails as read, unread, flag important emails, and delete or archive emails.

• Provide options for creating folders, moving emails between folders, and managing email settings.

• Consider res...read more

Performance improvement in React involves optimizing rendering, reducing bundle size, and utilizing memoization.

• Optimize rendering by using shouldComponentUpdate or React.memo

• Reduce bundle size by code splitting and lazy loading components

• Utilize memoization with useMemo or useCallback for expensive computations

HTML5 offers enhanced features, better semantics, and improved multimedia support compared to its predecessor, HTML.

• New semantic elements: HTML5 introduces elements like <article>, <section>, <header>, and <footer> for better document structure.

• Improved multimedia support: Native support for audio and video with <audio> and <video> tags eliminates the need for plugins.

• Canvas element: The <canvas> element allows for dynamic, scriptable rendering of 2D shapes and bitmap images....read more

Design a webpage using HTML/CSS

• Use semantic HTML tags for better accessibility and SEO

• Create a responsive layout using CSS Grid or Flexbox

• Apply CSS styling for colors, fonts, and spacing

• Use media queries for different screen sizes

• Optimize images for faster loading times