Front End Developers Interview Questions

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The article lists Front End developers interview questions.

With the growing needs of Front-End development, the MEAN stack is high in demand. It is a healthy career choice for the developers, and also businesses today started focussing on having a MEAN stack developers’ team for building large, complex, and interactive applications. Before onboarding your developers for MEAN Stack, few things need to be asked in a technical interview.

We will discuss below a few of those with the best possible answers so that you can prepare your resource screening planning accordingly. And we will take up the example of AngularJS here.


In Angular, how do you define a Routing Guard?

It is the interface that can instruct the router whether to allow navigation to a requested route or not. It decides the return value of the class in True or False value, and this class implements the Guard Interface.


How do you define a Service in Angular, and when will you use it?

Angular services are the objects which get instantiated at the time of global declaration, and it stays through the lifetime of the Application. These contain methods which, in turn, maintain data for the lifetime of an application. It makes the data available all the time with getting it refreshed. In an Angular application, this service assists in organizing and sharing the business logic, functions, and features, models within different components in use.


What are the new things found in Angular 6.0?

Elements – It lets you wrap the Angular components as Web components and can also embed them in a non-Angular Application.

New Rendering Engine – In Angular 6.0, due to the introduction of the New Rendering Engine, the speed has been improved, and overall performance has been more optimized.

RxJ6 – Angular 6.0 now comes with RxJ6 inbuilt, and it upgrades your old Angular syntaxes compatible with new library inclusions and syntax structure.

Animations – If you are not using AnimationBuilder, the polyfill web-annimation.js won't be necessary for creating the animations in Angular 6.0.


Describe AOT

AOT means Ahead-of-Time compiler. It helps pre-compiling application components and the templates during the build preparation. AOT helps in launching the Applications much faster. There are few reasons behind:

  • Without the client-side compilation, you cannot execute the components immediately
  • There lies no client-side request for template files as templates come embedded with the code
  • Unused Angular directives are automatically discarded


What is an Angular Expression?

These are the code snippets that are usually placed in binding. 


Can you point out some differences between JavaScript expression an Angular expression?

Yes, there are several to mention:

Context: In Angular, the expressions are evaluated against the scope objects, but in JS expression, these are done against the Global window.

Forgiving: Undefined properties in JS Expressions generate TypeError or ReferenceError while in Angular Expressions, it is returned as NULL or UNDEFINED.

Control Flow Statements: Conditional Loops and Exception Handling codes can't be included in Angular Expressions.


What is Data Binding in AngularJS?

Synchronization of data between the Model and View components is called Data binding. Two types of Data binding are found in AngularJS,

  • Data binding in classical templates
  • Data binding in Angular templates


Explain String Interpolation in Angular JS

During the compilation process, it matches the text and attributes using the Interpolation service to check if there is any embedded expression in the Angular Code.


Explain, what is an Injector

It is ideally the Service Locator. It retrieves the object instances, it activates the types, invokes the methods, and loads the modules.


Please elaborate on Link Compile functions in AngularJS.

Compile function is used for DOM manipulation and to collect all of the directives. Link function is used for registering DOM listeners and instances of DOM manipulations.


What is a factory method in AngularJS?

Factory Methods are generally used for creating the directive in AngularJS. When the compiler starts to match the guideline for the first time, this gets invoked only once.

Please elaborate on the concept of Scope Hierarchy. How many scopes can be there in an Angular Application?

In Angular, you would be able to find out one Parent or Root scope and many Child scopes. An Application, thus, can have multiple ranges. Upon adding new scopes, they come under the tree hierarchy and appear as child scope.


Apart from these above Interview questions, you can conduct a machine test also before you hire web developers. These two rounds of interviews will assist you in screening the Angular developers for your project requirement. Just remember one thing, the Angular framework gets very frequently updated. Hence, you need to provide such an environment for your Angular web developers that they get encouraged; they can keep updating themselves with the latest libraries, versions, syntax structures, etc.