If you’re searching for a top AngularJS developer to join your team, securing one can be the difference between buggy software that’s hard to modify and error-free software that’s easily modifiable.
Let’s begin by examining the benefits of enlisting an AngularJS developer or freelancer, and then dive deeper into the specifics. Once you’ve experienced the advantages of this approach, we’ll guide you on how to evaluate the AngularJS expertise of potential candidates during interviews.
Why Settle for Less? Hire a Seasoned Professional to Build Your Website or App with AngularJS
AngularJS is an all-inclusive front-end development solution that major corporations such as Google and Intel rely on for enhanced performance, accelerated development and reliable testing. Building data-driven web applications with AngularJS eliminates the need for any additional plugins or frameworks.
What Sort of Responsibilities Can You Anticipate from an AngularJS Developer?
- Develop innovative UIs, keeping in mind the capabilities of AngularJS’s robust framework.
- Prepare projects for product assessment.
- Collaborate with the backend developer to create the RESTful API, as suggested in this informative post.
- Ensure the application performance is optimum and the service is available 24/7, as suggested in this informative blog post.
- Aid single-page applications with their search engine optimization, as elaborated in this informative comparison post between Next.js and React for the year 2023.
- Develop AngularJS, Rest Web Service and Java application code, and perform unit tests for the ADC, as described in this helpful blog post on the qualities of competent Java programmers.
The Significance of AngularJS
By merging pre-built modules, AngularJS empowers developers to create applications.
Instead of using primary methods, AngularJS utilises modules to connect and initialise the various components of the program. These modules offer a descriptive representation of the application’s initiation procedure.
This simplifies the code, promotes the reuse of modules, enables specific module loading for unit testing, and improves performance, among other benefits. Because the modules halt execution until they are all loaded, all loading orders, including parallel, can be accommodated.
As a result, AngularJS assists developers by automatically identifying the requirements for objects such as a Facebook login module.
After determining the necessary modules, AngularJS can provide and integrate them. Since many of them already provide solutions to common problems and tasks, such as certain routing modules like ui-router, they save time and reduce the amount of code required.
Huge and Active Community
As an open-source platform, AngularJS has a robust community that is constantly adding new features to make the development process more accessible. Additionally, it’s worth mentioning that any inquiries one may have are likely to have been addressed on StackOverflow already.
Due to the widespread use of AngularJS, developers across the world have access to numerous educational opportunities, including Meetups, hackathons, and conferences devoted to this framework.
The declarative nature of AngularJS results in code that is easier to understand and maintain. In this coding style, the logic is expressed without including the control flow.
With AngularJS, developers can achieve the desired end product without specifying every individual step. This streamlines the review process when multiple individuals are involved, resulting in time savings.
Developed by Leading Engineers at Google
AngularJS was created by Google engineers Adam Abrons and Misko Hevery, resulting in a reliable, well-supported code base. The support of a major, established corporation distinguishes AngularJS from comparable frameworks such as KnockoutJS.
With AngularJS, HTML is used as the template language and incorporates various directives. These directives allow developers to design a customized HTML syntax for their application while creating reusable components that conceal complex DOM structures, CSS, and behaviors.
AngularJS allows developers to use HTML as if it were XML, eliminating the need to establish specific CSS classes for each object’s function. This offers greater flexibility without an increase in the number of classes. To distinguish between the visual and functional design of your application, the HTML compiler and directives in AngularJS make it easier to implement this approach in your code.
AngularJS was developed with built-in testing capabilities, eliminating the need for additional frameworks or plugins. Its controller and scope management implement Dependency Injection (DI), enabling data to be shared between controllers and facilitating effective testing of other elements of the application.
Dependency Injection (DI) has been shown to be extremely advantageous. In AngularJS, the injector subsystem allows developers to concentrate on the most critical aspects of their work: building components, controlling their dependencies, and making them available to other components as needed.
By isolating modules, it becomes quick and easy to test individual parts of your program. AngularJS provides pre-packaged functionality that allows services to be injected and mocked during unit testing, providing testers with a valuable tool.
AngularJS’s end-to-end scenario runner is crucial in minimizing the chances of test flakiness. This runner is proficient in its operations and aids in executing tests in an environment that closely mirrors production.
Combining Data Collectively
AngularJS’s two-way data binding instantly updates the front end to reflect any modifications made to the application’s objects. This process, also referred to as “automatically synchronizing data between the model and view components,” establishes the model as the primary source of information for the application.
Binding data couples the model components with the template to construct a view. Any modifications made to the model or view are not automatically reflected in the other. Consequently, developers must code continuously to synchronize the view with the model and the model with the view.
AngularJS generates a real-time view by first compiling the template in the browser during the compilation process. As a result, the model displays the current perspective as well as its inverse. This enables developers to work more rapidly and confidently, and testing is made simpler since controllers may be tested without the need for the view and its associated DOM/browser requirements.
Crucial AngularJS Interview Questions for 2023
If you believe that recruiting an Angular developer is beneficial, let’s discuss how to locate the top candidates for the position.
Arguments for AngularJS Scope.
The scope of an object can be regarded as the context in which an expression is carried out. Scopes form the basis of the application and are organized in a hierarchical manner, similar to the Document Object Model (DOM).
Scopes can be utilized to keep track of expressions and transmit events. Of all the features, some of the most notable include:
- APIs ($watch) are provided to monitor changes to a model.
- Scope nesting enables organizations to restrict access to specific sections of an application and their related data. Child scopes inherit attributes from their parent scopes, but isolation scopes do not, as their name implies.
- Implementing a Scope Assessment for Expressions
- The scopes API ($apply) may propagate model updates that were made outside of the AngularJS framework throughout the system and display them in the view.
Scope acts as an interface between the application controller and the view. Directives can be informed when a property has been modified during the template linking process by using $watch expressions. This allows the directive to update the DOM with the new value.
The directive and the Document Object Model (DOM) are both separate from the controller since controllers and directives do not share a direct reference. However, they do have a common reference to the scope, which helps maintain the controller’s independence, making it easier to test.
Applicants for an AngularJS role should have a thorough understanding of scope. $scope objects are heavily used in this framework to connect the application controller and view.
MyController may be utilized to assign the value ‘World’ to the scope’s username field and notify the input. The example should give a better understanding of how a controller can be used to input data into the scope.
Additionally, when connected to HTML input widgets, a scope’s properties can be quickly modified. The documentation offers another example, demonstrating how user action may trigger a behavior associated with the scope.
To understand “greeting” correctly, one must recognize the significance of the following:
- The scope linked to MyController initially can be retrieved, which corresponds to the scope of the Document Object Model (DOM) node where the term “greeting” is present in the template.
- Using the retrieved scope, apply it to the welcome expression and utilize the outcome as the text of the enclosing DOM element.
The scope contains all relevant details regarding the view, making it the most dependable source of reference. When the controller and view are separated, we can conduct trials without worrying about the rendering of the user interface.
In conclusion, the scope can monitor expressions and transmit events. It creates a connection between the controller and program’s view that closely mirrors the DOM.
Explain how $watch operates within the $digest cycle.
Aspirants must be familiar with the choices offered in this query, especially concerning the interconnectedness of the $watch and $digest functions.
To manually initiate the $digest cycle, you can utilize the $apply function. This function compares the present and previous $watch expressions and engages asynchronous processing. As a result, the $watch is not triggered instantaneously, but instead during the $digest phase.
This pause ensures that no other watches run at the same time as the notification being processed. Furthermore, if required, various model modifications may be combined into a single watch notification. Every time the watch value changes, the $digest cycle will repeat until all values are updated.
According to the AngularJS documentation, after the $apply procedure is finished, a $digest cycle is launched on the root scope and then extended to every child scope. During the $digest cycle, all watched expressions and functions are examined for model changes, and if any are found, the corresponding $watch listener is notified.
During this phase, any unnecessary sub-scopes are eliminated from the scope. It is crucial to halt these operations to conserve memory by halting further $digest calls to the child scope.
The first query’s topic is encompassed in this $digest cycle, which is a loop that updates the view each time the model is changed.
To sum up, the process begins with an event that modifies the value of the activity model. AngularJS data comparison is utilized to compare this data to previous values. If the values are distinct, the digestion process is initiated. During this iteration, all watchers in the scope are verified. When a model is updated, the digest cycle identifies which models have been updated using these monitors. Finally, this iteration is repeated (a ‘dirty check’) to ensure that the model and view are synchronized.
When interviewing for an AngularJS role, referencing the fact that excessive watchers may impede the digestion cycle and consume too much memory can earn you extra points. When a page has over 2000 visitors, it is deemed excessive.
Dissect the definition of “service” and how it adds value to the user.
In AngularJS, services are a universal mechanism utilized to organize and disseminate code throughout an application. They are also known as ‘substitutable objects’ that are linked by means of Dependency Injection (DI).
Objects that are instantiated lazily are not generated until needed by another section of the application. This can enhance the reliability of AngularJS programs and minimize the risk of encountering errors.
Services execute a particular operation, and any element that depends on a service will receive a pointer to the sole instance created by the service factory.
Services can be generated using either a factory or a service method. If the interviewee does not provide a clear differentiation between these two methods, kindly request them to elaborate. Our response is given below.
AngularJS enables the creation of business logic that is separate from the View logic it communicates with. The $http service, the $log service, and the $anchorScroll service are three of the most frequently utilized built-in services.
The $http service can connect to remote HTTP servers. The $log core server can be used by developers to securely transmit messages to the browser’s console. The $anchorScroll scrolls to the element associated with the given hash based on the value of $location.hash or takes no action.
One can evaluate a candidate’s grasp of services by asking them to enumerate some commonly used AngularJS services. These services have the dollar sign in their name and there are many available.
- Reference to the window object in the current browser ($window). (No change made as the content is already concise and clear.)
- With window.location, $location retrieves the browser’s address bar URL and makes it accessible to your program.
- The presentation of user-facing data is formatted using $filter.
- The $resource parameter is utilized to connect to Restful APIs.
- The $timeout variable provides access to the window.setTimeout method.
- We previously provided a detailed overview of the project’s scope. Every application has a unique root scope known as $rootScope, which serves as the foundation for all other scopes.
- $document is a jQuery or jqLite envelope around the window.document object available in the browser.
- An unmanaged exception in an AngularJS expression can be sent to the $exceptionHandler parameter. If an issue arises, it will be logged to the browser console using the $log.error function.
- The $parse directive can be employed to transform an AngularJS expression into a function with ease.
- $cacheFactory generates and enables access to cache objects.
Whilst it is unlikely that a candidate will remember every single one, they should be able to mention several that are essential to their day-to-day responsibilities.
Incorporating services that provide reusable components enables your app’s developers to build reusable APIs. Furthermore, it is feasible to inject one service into another via the AngularJS controller.
Injecting the data kept in one service into another controller is the most effective and uncomplicated method for exchanging data between controllers. It is also possible to access controllers directly via techniques like $parent or nextSibling for data transfer.
Nonetheless, it is advisable for your candidate to understand that employing services and a controller is the most effective technique as it makes testing easier.
What are the main differences between the Factory and Service methods?
Next, we will delve into the manufacturing and service industries. These two alternatives are offered to keep controllers and scopes detached from an application’s business logic and permanent data.
In this section, an illustration is presented to demonstrate the distinction between a service and a factory function. Both of these approaches will result in output of the term ‘hello,’ however, the principal difference is in the commands given before printing the term. A service is a constructor function, whereas a factory is a function that must be invoked.
Using ‘this’ in the service example, but not in the factory example, is an effective approach to comprehend this divergence. Instead, it is necessary to return the factory object directly.
Our approach includes utilizing examples such as the use of “
$injector.instantiate()) as the method that employs
Object.create() with the constructor function,” and “a service that invokes a pre-defined factory, ultimately becoming the $get()$get() method on the corresponding provider,” to evaluate a candidate’s ability to articulate complex concepts in a succinct and understandable fashion. That is why these examples are incorporated into our offerings.
How Flexible are the AngularJS Service Creation Techniques? If You Could Elucidate, that Would Be Superb.
Collectively, AngularJS refers to these five methods as “recipes,” which are Factory, Service, Provider, Value, and Constant.
When exploring Factory, it was revealed that additional services can be incorporated into it once it is constructed. In comparison to other approaches like the Value recipe, Factory has the added benefit of being able to incorporate dependencies, use other services, and launch service start-up.
For the Factory recipe, two arguments are obligatory: a string (the service’s name) and a function (the code). This string can be utilized to inject the service into a controller. When the service is registered, Angular will execute the function once.
Subsequently, the cached outcome can be utilized by the rest of your app’s injectable services.
The Factory method does not only initiate the function, unlike the Service technique, but also actually executes the callback function. Depending on the type of service being created, different dependencies or methods may be injected into it. In this case, the function must return an object, with the specified name being returned.
Now, let us examine the controller applications for this Factory service. It can be observed that the username for the scope is identical to the one employed in building the Factory.
Developers may construct and utilize this service to hold a solitary value. This method creates a globally accessible, injectable Angular service, making the value easily accessible and testable throughout the application.
This technique is utilized to establish constants that can be called upon when declared as a dependency. It is not solely relevant during the initial configuration of the application but can also be utilized at later points.
This service is frequently employed for common values like “application name” and “base URL.” As these constants cannot be modified, they should only be specified once and then utilized wherever necessary.
The Service technique bears a close resemblance to the Factory approach. By utilizing the ‘this’ keyword in the Service recipe, the attributes and methods of the object that the Service returns can be specified. This is possible since it is instantiated rather than executed.
The fifth option, the Provider method, is somewhat more intricate when compared to the other four. To be precise, it is the precursor of all service types that AngularJS supports (excluding a Constant).
This approach serves as the basis for the other service categories. Although more detailed than the other methods, it offers a range of advantageous features. It can be accessed during the setup phase of an application, which can prove useful if the service is to be used by multiple applications that need to be correctly configured.
To obtain the injectable object, the `$get` method must be implemented in this versatile service. This service may be utilized to offer the application-wide configuration API.
It should be noted that the callback function for this technique is created per application it registers with, and the resultant value is shared among all components that employ the service. The Provider approach utilizes the provided callback function as a constructor.
To avoid potential conflicts with future standards, it is advisable to prefix one’s own directive names. An example in the Developer Guide exhibits how directive creation could lead to problems if the same element were added in HTML7. To ensure best practices, it is recommended to utilize a prefix of two or three letters (such as ‘btfCarousel’).
Elucidating the Distinctions Between Unit Testing and End-to-End Testing
While testing may present challenges, AngularJS equips its users with an assortment of tools to facilitate the process.
Unit testing encompasses assessing individual code sections to answer questions such as “Is my approach logical?” and “Does the sorting algorithm yield precise results?”.
Developers widely acknowledge that the sorting functionality cannot be sufficiently tested if components like DOM elements or XHR requests are utilized to obtain the data. Therefore, it is imperative to isolate the pertinent code to ensure successful testing of the sorting feature.
Testing individual functions or methods while preventing the code from executing complex tasks like making an XHR call, sorting the data returned, and altering the Document Object Model (DOM) can prove challenging, even for individuals well-versed in the concept of separation of concerns.
By providing dependency injection for XHR requests and an abstraction layer over the DOM, AngularJS expedites code modularization and aids in testing, allowing models to be tested without directly manipulating the DOM.
The tests should not generate or scrutinize the Document Object Model and its associated state, nor should they evaluate the XMLHttpRequests and the data they yield. Instead, it is feasible to verify whether the data is being arranged correctly.
Candidates should exhibit a comprehensive comprehension of dependency injection, an indispensable feature of AngularJS. Additionally, they should illustrate an awareness of the significance of testing in all applications, and elucidate how AngularJS streamlines the testing process.
Developers can replace or simulate a component’s dependencies using dependency injection. With injected component dependencies, it can be effortlessly mocked for each test without affecting other tests with any changes to global variables.
Within AngularJS, the Injector manages component construction, resolves the dependencies, and supplies them to other components as required. The Injector can be employed in multiple areas, including component definitions, execute and config blocks.
An injectable factory method or constructor function can specify the definition of any form of component, including a directive, filter, service, or animation. Afterward, services and values can be injected as dependencies into these modules.
Controllers, defined by a constructor function, can inject services and value components as dependents. Support systems can be established for them if needed. An executable function can be dispatched to the run method, with additional services, values and constant dependencies being injected into this function using the ‘inject’ keyword. Providers, however, are not permitted in run blocks.
Ultimately, a function can be supplied to the configuration method. In its configuration, only “provider” and “constant” components can be injected as dependencies, whereas “service” and “value” components are not permitted.
Testing an AngularJS filter is simple. Inject the filter into the module, provide any essential mocks, obtain a filter instance via $filter(‘filterName’), and then test your hypotheses.
AngularJS’s dependency injection streamlines testing, rendering it more effective. Nonetheless, creating a unit test in isolation can be difficult, as it can be challenging to establish and mock the required dependencies. To evaluate a candidate’s familiarity with this topic, it is advisable to inquire with them.
Moving ahead, let us delve into end-to-end testing with AngularJS. It is crucial to note that the AngularJS Scenario Runner, previously utilized for full-stack testing, has been decommissioned and is currently unavailable for maintenance.
Manual testing may not always be feasible, particularly for businesses with large or complex software programs. Regrettably, as the program’s size grows, so does the frequency of bugs. Although end-to-end testing (e2e testing) may be conducted manually, it is also possible to outsource it to a continuous integration service. These services can be custom made or bought from a vendor.
Unit tests can be an effective approach to identifying issues, but certain bugs may elude detection during this process. AngularJS introduces end-to-end testing as an additional measure to help discover any remaining bugs. Protractor is an end-to-end test runner that can simulate user interactions and find flaws that may have gone unnoticed during unit tests.
End-to-end tests are commonly executed on a fully functioning live application system. This frequently necessitates launching a new browser, which entails entering user commands via an interface.
To execute the code, a webdriver or similar automation tool can be utilized to give commands to a running browser instance. An assessment can then be based on the observable outcomes, followed by handling assertions using Jasmine or another library.
A test file in end-to-end testing often consists of at least one ‘it’ block, identical to a unit test file. This group of directions and presumptions defines the parameters of your program.
Protractor is directed to make assertions on the application’s state, such as a certain number or URL, based on a pre-established set of assumptions. This allows it to perform tasks within the application, like selecting a menu item or navigating to a specific page.
Using the beforeEach and afterEach blocks, files can be directed to perform tests either before or after an IT block. These blocks will execute irrespective of the block’s success or failure, although the runner typically designates the IT block as “failed” if any of its expectations are not met.
End-to-end (e2e) testing is a type of validation that comes after unit tests. It runs the program from start to finish in order to detect any additional issues. Once these tests have been implemented and the necessary modifications made, the application should be fully operational, particularly in terms of integration and flow.
It is imperative to verify that the candidate is well-versed in both end-to-end testing and Protractor, an AngularJS-based tool frequently utilized for e2e testing. Notably, the interviewee does not have to specifically use Protractor for e2e testing, as there are other alternatives available.
Please provide a definition of AngularJS Directives.
Directives refer to labels that are assigned to DOM nodes. An example of this is a CSS class, although other labels, such as attributes, element names, comments, and CSS comments, can also be utilized. These directives instruct AngularJS’s HTML compiler to perform an action, such as modifying the DOM element and its children, or more commonly, adding a particular behavior to the DOM element through event listeners.
An understanding of directives is of utmost importance in AngularJS. Therefore, it is reasonable to anticipate that your candidate has a strong comprehension of this topic.
AngularJS has the ability to produce custom directives, much like creating your own controllers and services. When initiating your application, the HTML compiler scans the DOM in search of directives to match with the DOM elements, as described in their Developer Guide. For more information on this topic, please see our blog post “Achieving the Optimal Rate of Innovation.”
It is important for candidates to recognize the diverse possibilities that directives present. They play a critical role in defining the user interface of single-page applications and can be integrated into individual widgets. Essentially, they enhance the capabilities of HTML by appending additional attributes prefixed with the ng-prefix.
Familiarity with commonly used built-in directives is desirable in candidates, but it is crucial that they possess the skills to design custom widgets. An illustration of this is ngBind, which enables AngularJS to substitute the text content of a designated HTML element with the value of a given expression and to update the text content whenever the value of the expression alters.
The ngModel directive produces and reveals a NgModelController, connecting an input, select, textarea (or customized form control) to a property on the scope.
The last crucial directive is NgClass. It is probable that the interviewee is sufficiently acquainted with this functionality to recollect the directive for “dynamically setting CSS classes on an HTML element by binding an expression that specifies all classes to be added.”
Before attempting to create a directive, it is crucial to comprehend how AngularJS’s HTML compiler determines when to use one. As the saying goes, “a directive is considered part of an element’s declaration if it matches it.”
The subsequent code illustrates that the input element meets the requirements of the ngModel directive in AngularJS: ng-model=”foo”.
The data-ng-model=”foo” attribute signifies that this input element is compatible with the AngularJS ngModel directive. The attribute name is also associated with the person directive.
AngularJS standardizes the tag and attribute names of elements to distinguish which are linked with particular directives. Because HTML is case-insensitive, the DOM always employs the lowercase form of the directive’s name. It is frequent to observe the use of dash-delimited characteristics, such as ng-model.
The module.directive API is used to register directives on modules, comparable to registering controllers. The API requires the normalized directive name (as discussed previously) followed by a factory function. The factory function should provide an object with settings that notify the compiler of how the directive should conduct itself when encountered.
When the compiler initially discovers a matching directive, the factory function is called, enabling initialization tasks to be performed. This function becomes an injectable controller by using $injector.invoke to execute it.
It is also recommended to steer clear of using the ng prefix for custom directives to circumvent possible conflicts with the pre-existing AngularJS directives.
Hiring an AngularJS Developer in 14 Days or Less
To discover a highly proficient AngularJS developer who can fulfil your company’s requirements, it is crucial to inquire about the appropriate aspects during the interview procedure. At Works, we are here to aid you in finding the ideal candidate for the position, so feel free to contact us and let us assist you in locating the perfect AngularJS developer for your team.