Question

Why should we use Angular 2 instead of React, Angular 1, backbone etc?

Answer

Using or not using Angular 2 for project depends on scope of your app. Using Angular 2 would help in cases where we want to create single page AJAX application to support mobile and desktop browsers.

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Question

What problem is Angular 2 trying to solve?

Answer

Angular 2 is providing MVVM and MVC architecture for browser Javascript code management. It provides modules for isolating application code, routing between controllers, dynamic template loading and extending HTML markups in terms of components and directives.

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Question

What benefits does .ts provide over legacy JS?

Answer

TypeScript provides all qualities and functionalities of Javascript; other than this it provides extended qualities such as static type casting which improve code execution efficiency. TS is compiled to Javascript before running on browser, which improve page render time etc.

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Question

Why are decorators used in Angular 2?

Answer

Decorators are used as identifier of class or type of object that is being created in TypeScript. Angular 2 identifies class below decorator call as definition of class and extend decorator specific properties with class definition.

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Question

What is root module for Angular 2 and what are its parameters?

Answer

@ngModule is the root module or class for an angular application. It is identified with decorator @ngModule and identifies the entry point of an application. It takes an object as parameter whose properties are imports, exports, declarations, providers, bootstrap.

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Question

How does angular 2 keep track of two-way data binding?

Answer

Angular 2 runs script for checking model stored values against displayed HTML values once per Javascript event cycle for whole application tree. If any value has changed on either side it replace the value to make them consistent. [(ngModel)]=”foo” is used as two-way binding attribute.

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Question

What limits the number of two-way binding attributes in Angular 2?

Answer

Too many two-way binding attributes can cause performance concerns in application. Each data binding pushes an event in Javascript event loop messages que, and pushing too many messages can block event loop and browser window.

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Question

How is using two-way data binding encouraged in Angular 2?

Answer

Using two-way binding within the scope of component only is encouraged. If a model receive too many inputs, its resolution can create inaccuracy.

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Question

What is difference between component and directive in Angular 2?

Answer

Component is a directive with template. Directive doesn’t have a template, while components have. Directives are identified with @Directive decorator while components are identified as @Component.

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Question

How can we bind a variable with DOM element in Angular 2?

Answer

Angular 2 provides this feature with ‘#foo’ syntax. A variable resembles Javascript DOM element and can be referenced in controller as well as DOM. i.e.

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Question

What can be considered as replacement of $watch in Angular 2?

Answer

ngOnChanges lifecycle hook can be considered as replacement of $watch in Angular 1. This hook is invoked every time angular identifies a change in components input model with two parameters; currentValue, oldValue.

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Question

What are pipes in Angular 2?

Answer

Pipes are used in templates to convert output to user friendly and readable form within interpolation braces i.e. {{ release | date }}. The ‘|’ is denoted as pipe.

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Question

Can we automate porting Angular 1 code to Angular 2?

Answer

No, currently there is no such tool available. Porting Angular 1 code to Angular 2 code will include side by side manual conversion of Angular 1 directives to Angular 2 components because they are two different approaches to solve the same problem and hence two different frameworks.

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Question

Which Angular 2 directive can be used for internationalization?

Answer

i18n is the Angular 2 directive that is used for internationalization i.e. conversion of static HTML text in multiple languages.

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Question

What is Host Decorators in Angular 2?

Answer

Host decorators bind properties of component with UI element values. The properties inside component class definition decorated with @HostBinding can be accessed in template from assigned property i.e. @HostBinding() title = ‘My Title’.

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Question

What are Observables in Angular2

Answer

Observables in Angular 2 are similar to promises but with major differences that make them better. Observables handle multiple values over time which makes them a good candidate for working with real-time data. Observables can also be cancelled and this gives a better control when working with in-flow of values from a stream. Observables is an ES7 feature which means you need to make use of an external library to use it today. For example, RxJS - https://github.com/Reactive-Extensions/RxJS.

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