24. What are pipes in AngularJS?#
Pipes in AngularJS provide a simple method for transforming data within applications. They are versatile functions that can be utilized in template expressions to format and manipulate data dynamically. Pipes take an input value and return a transformed output, making data presentation more flexible and user-friendly.
AngularJS offers several built-in pipes, such as uppercase
, lowercase
, date
, and currency
, but developers can also create custom pipes to meet specific application needs. Pipes work by converting data into the specified format, enhancing the user interface of AngularJS applications.
To create and use a pipe, we use the pipe character (|
) followed by a filter within a template expression. For example:
<p>Their full name is {{ lastName | uppercase }}</p>
The above code snippet demonstrates how the uppercase
pipe transforms the lastName
variable to uppercase letters in the rendered output. Utilizing pipes effectively can significantly improve the data presentation and user experience in AngularJS applications.
25. What are isolated unit tests?#
In AngularJS, an isolated unit test involves checking the instance of a class without using injected values or dependencies. Unit testing is a crucial practice in software development, where we are focused on testing individual units of code to ensure they function correctly. To conduct effective software testing, we must isolate the unit we want to test. This approach helps avoid complications, such as making XHR calls to fetch data or interacting with external services.
Isolated unit tests allow developers to independently verify the behavior of specific components or services in AngularJS applications. By mocking dependencies, we can ensure that the tests are focused solely on the logic of the unit being tested, leading to more reliable and maintainable code. Implementing isolated unit tests enhances code quality and helps identify issues early in the development cycle.
26. What is the difference between Angular and AngularJS?#
AngularJS and Angular (2+) are both frameworks developed by Google, but they differ significantly in terms of architecture, performance, and development approach. Here are some key differences:
- Architecture: AngularJS follows an MVC (Model-View-Controller) pattern, while Angular (2+) is built on a component-based architecture that promotes modularity and reusability.
- Language: AngularJS is written in JavaScript, whereas Angular uses TypeScript, a superset of JavaScript that provides better tooling, type safety, and maintainability.
- Performance: Angular delivers better performance and faster rendering due to features like ahead-of-time (AOT) compilation, a virtual DOM, and optimized change detection.
- Data binding: AngularJS primarily relies on two-way data binding, while Angular offers one-way data binding by default and two-way data binding when needed, improving efficiency.
- Dependency injection: Angular has a more structured and modular dependency injection (DI) system, making it easier to manage dependencies across applications.
- Mobile support: AngularJS was designed primarily for desktop applications, while Angular supports both web and mobile development, with optimized performance for modern browsers.
27. How does the angular.Module work?#
The angular.Module
is a crucial part of the AngularJS framework, serving as a global container for creating and registering modules. Any modules available to an AngularJS application must be registered with angular.Module
to be utilized effectively within the app.
When using angular.Module
, passing a single argument will retrieve an existing AngularJS module, while passing multiple arguments creates a new AngularJS module. This functionality allows developers to efficiently organize and manage the application’s components, services, directives, and other dependencies, facilitating better code structure and modular development within the AngularJS ecosystem.
There are several methods to enhance the performance of an AngularJS application. Two officially recommended practices for production environments include enabling strict dependency injection (DI) mode and disabling debug data.
Enabling strict DI mode can be achieved by setting it as a directive, like this:
<html ng-app=“myApp” ng-strict-di>
Disabling debug data can be accomplished using the $compileProvider
configuration, as shown below:
myApp.config(function ($compileProvider) {
$compileProvider.debugInfoEnabled(false);
});
In addition to these methods, other popular strategies for improving AngularJS app performance include:
- Utilizing one-time binding (when possible) to minimize unnecessary updates.
- Configuring
$httpProvider
to use applyAsync
for handling HTTP requests more efficiently.