Angular 4 Interview Questions and Answers
Angular 4, released in March 2017, is a JavaScript framework for building apps in HTML, JavaScript, and TypeScript. Angular 4 offers built-in features for HTTP service, animation, and materials. This is an essential topic in the Angular 4 Interview Questions for experienced professionals. The unique feature in Angular 4 is that starting from Angular 4, developers will be able to query ParamMap in the router.
| Quick Facts About Angular 4 | |
|---|---|
| What is current angular version? | Angular 11.0. released on 11th November 2020 |
| Angular4 is Developed by | |
| What language does Angular use? | TypeScript |
| When was Angular first released? | 20th October 2010 |
| When was Angular4 released? | 23rd March 2017 |
| Which is the best free IDE for Angularjs? | Sublime Text, Visual Code, Atoms, etc |
| What is the best Angular version of web development? | For the development, Angular 2 and 4 both are good. |
Most Frequently Asked Angular 4 Interview Questions
If Else statement in Angular 4 can be written using following syntax-
Open /src/app/app.components.ts:Export class AppComponent {
Title – ‘app works!;
}
Open /src/app/app.component.html
<div *ngIf = “ title; else login”>
The user is logged in. </div>
<ng-template #login> in order to login pleae continue. </ng-template>
Then statement can be write using following syntax-
<div *ngIf = “title; then logout else login “> </div><ng-template #login> please login to continue . </ng-template>
<ng-template #logout> Hi abc, <button> logout now </button> . </ng-template>
In Angular 4, the ForRoot method is used when the module is "eager," not lazy-loaded. Except for lazy modules that loaded on-demand with their factory, Angular creates a factory for all other modules. The ForRoot method allows users to access providers from any point in the application that is not lazy-loaded. This ultimately will enable users to have different configurations for different load cases.
Angular 5 has plenty of new features. Few of the most important ones are mentioned below:
- Addition of a build optimizer which removes unnecessary applications and codes.
- Support for DOM and Angular Universal State Transfer API.
- Optimized standardization across various browsers.
- Addition of a new HttpClient and lifecycle events router.
- Creation of Angular 5 projects by default with CLI 1.5.
- Multiple name support for directives and components.
In Angular 4, components have their view, whereas directives are just “behavior” added to the existing components and elements. Simplifying it, components extend directives. There can be many directives on a host element, but only one component.
In Angular 4, template reference variables allow users to access an instance of a directive or component or a DOM present in the template. These are defined by a hash sign (#) combined with a name as an additional DOM element’s attribute.
In AngularJS, JSON Web Token is used to send information that can be trusted and verified using a digital signature. The JSON Web Token comprises a URL-safe and compact JSON object, which is cryptographically signed to verify its authenticity. This also can be encrypted if the payload contains any sensitive information.
Yes, angular 4 services is a compiler which transverse the DOM looking for attributes. The process of compilation is partitioned into two phases namely-
Compile- means to traverse the DOM and gather all directives such as ng-repeat.
Link- means to produce a live view by combining the directives with a scope.
abstract class EmbeddedViewRef<C> extends ViewRef {
abstract context: C abstract rootNodes: any[]
}
In Angular 4, Map is a data structure used for mapping keys to values without the limitations involved in using objects. A Map can be created with the help of a new keyword and then various entries can be added to increase the functionalities with the help of a set method. This data structure is also chainable. A map can be initialized with the help of an array of key-value pairs.
Traceur compiler is compilers which use ECMAScript Edition 6 (ES6) that compiles the regular javascript which runs on user’s search engine.
Number of ways to use traceur compiler.
- Typing ES6 code in the page Read-eval-print-loop.
- In web page include Traceur and compile ES6 script content on the fly.
- Use node to compile ES6 to ES5 offline.
- Include the result in Web pages or just execute the result in angular 4.
This means a request for the route- and the query parameter can be assigned to a route. Until Angular 2, route parameters were stored in a key-value object and were accessible through standard JavaScript syntax. Do you want to succeed in your Angular 4 Interview Questions and Answers? Read on!
Another unique feature is that the functions that were necessary for animations are placed in their package. This has been done to avoid creating unnecessary bundles of significant size. Until Angular 2, these functions were offered as part of the core module and were always included even if they were not getting used in apps.
In angular 4, the use of decorators is done extensively for compiling the code. There are four types of decorators – Class, Property, Method, and Parameter.
Type security and speed ngc-Compilerhave improved in Angular 4 as compared to Angular 2. If you are scrolling on the web for angular 4 interview questions and answers pdf, then this guide will gonna help you.