Senior UI Engineer Interview Questions and Answers

List virtualisation optimises rendering by only rendering items that are currently visible on the screen.

• Use virtual scrolling to render only the visible items in a list

• Implement windowing techniques to dynamically load and unload items as the user scrolls

• Utilize libraries like React Virtualized or Angular CDK Virtual Scroll for efficient list rendering

Pseudo elements are used to style specific parts of an element, while pseudo classes are used to style an element based on its state or position.

• Pseudo elements are denoted by :: before the element name, like ::before or ::after

• Pseudo classes are denoted by a single colon before the class name, like :hover or :active

• Pseudo elements are used to style parts of an element that do not exist in the DOM, like adding content before or after an element

• Pseudo classes are used to style...read more

Inline elements do not start on a new line and only take up as much width as necessary, while block elements start on a new line and take up the full width available.

• Inline elements do not force a new line to start and only take up as much width as necessary (e.g. <span>, <a>, <strong>).

• Block elements always start on a new line and take up the full width available (e.g. <div>, <p>, <h1>).

• Inline elements can have margin and padding applied horizontally but not vertically.

• Block...read more

The output of typeof Symbol is 'symbol', indicating its unique data type in JavaScript.

• Symbols are a primitive data type introduced in ES6.

• They are unique and immutable, making them ideal for object property keys.

• Example: const sym = Symbol('description'); typeof sym; // 'symbol'

• Symbols can prevent name clashes in object properties.

Sorting algorithm is a method of arranging elements in a specific order.

• There are various sorting algorithms such as bubble sort, selection sort, insertion sort, merge sort, quick sort, etc.

• Sorting algorithms can be categorized as comparison-based or non-comparison-based.

• Efficiency of sorting algorithms is measured in terms of time complexity and space complexity.

Directives in AngularJS allow you to create custom HTML tags and attributes that extend the functionality of HTML.

• Directives are markers on a DOM element that tell AngularJS to attach a specified behavior to that DOM element.

• They can be used to create reusable components, manipulate the DOM, and add interactivity to an application.

• Examples of directives include ng-model, ng-show, ng-hide, ng-repeat, and custom directives created by the developer.