Angular 4 Interview Questions and Answers

Angular 4 is the upgraded version of AngularJS, which is the very first introduction of AngularJS. The newer version Angular 4 has fulfilled several drawbacks of its predecessor and introduced excellent features such as Router ParamMap support, Dynamic Components with NgComponentOutlet, latest TypeScript functions, simplified HTTP request, better Animation package, mobile-oriented framework, server-side run and more, which were are not available with the AngularJS.

While creating an Angular 4 component, a shadow DOM is created by default and our template gets loaded into it. It’s a DOM element subtree which renders as part of the document but not into the present main document DOM tree. It is used by browsers to determine the rendered object on the page. JavaScript programs use it to modify content, page styling and structuring.

To debug Angular 4 projects using visual studio 2017, we have to follow the below-mentioned steps.

• Create our project as Asp.Net Core Web Application and use the “Angular” project template.
• Next to "IIS Express", click the down-arrow to set the web browser to Google Chrome.
• Run debugging and the script debugging being enabled message will pop up by Chrome.
• Continue further by setting a breakpoint on "this.currentCount++;"in counter.component.ts.
• Now visit the Counter screen to click Increment and the breakpoint set will be hit.
• While performing this, make sure to turn off the Chrome Developer Tool running

Note- make sure that your chrome developer tools will run on the same time during the process of debugging

We need Ngmodel in angular 4, as it possesses the property of binding and encapsulating the input elements of DOM. In short, we need Ngmodel in angular 4 for two –way-data-binding process.

Angular 4 is an advanced JavaScript framework which uses HTML, JavaScript, and TypeScript web applications and APK apps. It’s a superset of JavaScript and offers excellent built-in features for HTTP service, animation, navigation, menus, toolbar, materials, etc.

Here are a few significant differences between Angular 2 and 4 which developers are going to notice.

• Angular 4 has many inbuilt animation packages which were missing in Angular 2.
• Angular 4 has its template tag called “ng-template.” The previous version uses only “template.”
• Compared to Angular 2, in the newest version, developers can use else syntax with Nglf for excellent UI handling.
• A new template syntax addition “as keyword” in Angular 4 which can be used to simplify to the “let” syntax.
• Simplified “HTTP request” and application testing in Angular 4.

AngularJS is the very first version of the Angular. A tool named AngularCLI is used to generate Angular components. Angular JS which is a client-side framework works with JavaScript and still supported but not compatible with Angular any more. Simplifying it, AngularJS is the old version and Angular is the newest one.

To set Http Request Header in Angular 2, create the HTTP Client Injectable class and inject the HttpClient object in the Component. Developers use HTTP Interceptors to set Http Request Header in Angular 4. To achieve this. Write an interceptor for adds a header for every request and after creating the interceptor, register it using HTTP_INTERCEPTORS in the @NgModule().

To create a new component in Angular 4 using CLI,

• Open Project Directory
• Run any one of the below mentioned the syntax

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No coding level changes are required to enhance a project present in Angular 2 to Angular 4. Users only have to update the tsconfig.json and package.json files. Some minor adjustments may be needed depending on project types. After updating the data, clean out your node_modules directory, run npm install and npm start and you will be started with the Angular 4.