Primary Health Centre Web Developer Interview Questions and Answers

Hoisting is a JavaScript mechanism where variables and function declarations are moved to the top of their scope.

• Hoisting applies to variable and function declarations, but not to variable assignments

• Function declarations are hoisted before variable declarations

• Hoisting can lead to unexpected behavior and should be avoided

var is function-scoped and let is block-scoped.

• var declarations are hoisted to the top of their scope, while let declarations are not.

• var can be redeclared in the same scope, while let cannot.

• let variables are not accessible before they are declared, while var variables are.

• let variables have a temporal dead zone, while var variables do not.

• let is recommended for use in modern JavaScript.

Optional chaining is a feature in JavaScript that allows you to access properties of an object without worrying about whether the object is null or undefined.

• It uses the question mark (?) operator to check if a property exists before accessing it.

• It can be used with both object properties and function calls.

• It can be chained multiple times to access nested properties.

• It was introduced in ECMAScript 2020.

Pseudo elements/children are CSS selectors that target specific parts of an element.

• Pseudo elements are denoted by a double colon (::) and are used to style a specific part of an element, such as the first letter or line of text.

• Pseudo children are denoted by a single colon (:), and are used to select a specific state of an element, such as when it is being hovered over or clicked.

• Examples of pseudo elements include ::...read more

Closure is a function that has access to its outer function's variables, even after the outer function has returned.

• A closure is created when a function returns another function that references variables from the parent function.

• Closures can be used to create private variables and methods in JavaScript.

• Closures can also be used to create functions with pre-set arguments.

JavaScript is a programming language used for web development, while Angular is a JavaScript framework for building web applications.

• JavaScript is a programming language that allows developers to add interactivity and dynamic features to websites.

• Angular is a JavaScript framework that provides a structure for building web applications.

• JavaScript can be used independently to create web functionality, while Angular is bu...read more

TypeScript is a superset of JavaScript that adds static typing and other features.

• TypeScript catches errors at compile time, while JavaScript only catches them at runtime.

• TypeScript supports interfaces and classes, making it easier to write and maintain large codebases.

• JavaScript is more flexible and easier to learn, but TypeScript offers better scalability and maintainability.

• TypeScript can be transpiled into JavaScri...read more

A service in Angular is a singleton object that can be injected into components and other services.

• Services are used to share data and functionality across multiple components

• Services can be used to make HTTP requests, handle authentication, and perform other tasks

• Services are typically defined using the @Injectable decorator

• Services can be injected into components and other services using the constructor

Angular app bootstraps the root module of the application

• Angular app bootstraps the AppModule by default

• The bootstrap process initializes the application and loads the root component

• The root component is usually AppComponent

Components can interact in Angular through input and output bindings.

• Input bindings allow a parent component to pass data to a child component.

• Output bindings allow a child component to emit events to a parent component.

• Components can also communicate through a shared service or using @ViewChild and @ContentChild decorators.

Lifecycle hooks are functions that allow you to tap into the lifecycle of a component or directive.

• ngOnInit() - called after the first ngOnChanges()

• ngOnChanges() - called when an input property changes

• ngDoCheck() - called during every change detection run

• ngAfterContentInit() - called after content is projected into component

• ngAfterContentChecked() - called after every check of projected content

• ngAfterViewInit() - calle...read more