Let’s jump in!<\/p>\n\n\n\n
Looking to hire the best remote developers? Arc can help you:<\/em><\/p>\n\n\n\n \u26a1\ufe0f Get instant candidate matches without searching Try Arc to hire top developers now \u2192<\/strong><\/em><\/a><\/p>\n\n\n\n Dependency injection is a powerful software design pattern that Angular employs to compose responsibilities through an intrinsic interface. However, for those new to the process, it can be puzzling where you need to configure and mock these dependencies when creating your isolated unit tests. The open-source project \u201cAngular Test Patterns\u201d is a free resource that is focused on dispelling such confusion through high-quality examples.<\/p>\n\n\n\n This question is useful since it can give you a feel for how familiar the candidate is with automated testing (TDD, BDD, E2E), as well as open up a conversation about approaches to code quality.<\/p>\n\n\n\n Sources:<\/strong> TL;DR Summary: To reduce memory consumption and improve performance, limit<\/strong> the number of watches on a page to 2,000. A utility called\u00a0 Jank happens when your application cannot keep up with the screen refresh rate. To achieve 60 frames-per-second, you only have about 16 milliseconds for your code to execute. It is crucial that the scope digest cycles are as short as possible for your application to be responsive and smooth. <\/p>\n\n\n\n Memory use and digest cycle performance are directly affected by the number of active watches. Therefore, it is best to keep the number of watches below 2,000. The open-source utility Caution:<\/strong> Be wary of relying on a \u201csingle magic metric\u201d as the golden rule to follow. You must take the context of your application into account. The number of watches is simply a basic health signal. If you have many thousands of watches, or worse, if you see that number continue to grow as you interact with your page. Those are strong indications that you should look under the hood and review your code.<\/p>\n\n\n\n This Angular interview question is valuable as it gives insight into how the candidate debugs runtime issues while creating a discussion about performance and optimization.<\/p>\n\n\n\n Sources:<\/strong> Create an AngularJS service that will hold the data and inject it inside of the controllers.<\/p>\n\n\n\n Using a service is the cleanest, fastest, and easiest way to test. However, there are a couple of other ways to implement data sharing between controllers, like:<\/p>\n\n\n\n \u2013 Using The methods above are all correct, but are not the most efficient and easy to test.<\/p>\n\n\n\n We only need to keep in mind the difference between these directives. Developers can decide which one to use depending on the task requirements.<\/p>\n\n\n\n In each digest cycle, Angular compares the old and the new version of the scope model values. The digest cycle is triggered automatically. We can also use For more information, take a look at the ng-book explanation: The Digest Loop and $apply<\/a><\/p>\n\n\n\n Struggling with interview prep? Meet senior developers from Amazon, Microsoft, and Google now on Codementor. They\u2019ll help you tackle coding challenges, practice interviews, and sharpen your skills in live 1:1 sessions. Explore our other software development interview questions and answers to prep for your next remote job.<\/p>\n\n\n\n In the directives. DOM Manipulations should not exist in controllers, services or anywhere else but in directives.<\/p>\n\n\n\n Here is a detailed explanation<\/a>.<\/p>\n\n\n\n It is definitely a bad practice. Developers need to avoid jQuery and try to realize the solution with an Angular approach. jQuery takes a traditional imperative approach to manipulating the DOM, and in an imperative approach, it is up to the programmer to express the individual steps leading up to the desired outcome.<\/p>\n\n\n\n AngularJS, however, takes a declarative approach to DOM manipulation. Here, instead of worrying about all of the step-by-step details regarding how to get the desired outcome, we are just declaring what we want, and Angular will take care of everything for us.<\/p>\n\n\n\n Here is a detailed explanation<\/a>.<\/p>\n\n\n\n Changing By using \u201c Basic Angular interview questions like this one are asked to assess your knowledge of HTML attributes, DOM properties, and other syntax-related aspects.<\/p>\n\n\n\n Source:<\/strong> https:\/\/docs.angularjs.org\/api\/ng\/type\/$rootScope.Scope<\/a><\/p>\n\n\n\n The It creates a deep copy of the variable.<\/p>\n\n\n\n A deep copy of a variable means it doesn\u2019t point to the same memory reference as that variable. Usually assigning one variable to another creates a \u201cshallow copy\u201d, which makes the two variables point to the same memory reference. Therefore if one is changed, the other changes as well.<\/p>\n\n\n\n Sources:<\/strong> To add promise functionality to a service, we inject the \u201c$q\u201d dependency in the service, and then use it like so:<\/p>\n\n\n\n The Source:<\/strong> https:\/\/docs.angularjs.org\/api\/ng\/service\/$q<\/a><\/p>\n\n\n\n AngularJS Services are objects that provide separation of concerns to an AngularJS app. These can be created using a factory method or a service method. Services are singleton components and all components of the application (into which the service is injected) will work with single instance of the service. An AngularJS service allows developing of business logic without depending on the View logic which will work with it.<\/p>\n\n\n\n Few of the inbuilt services in Angular are:<\/p>\n\n\n\n Services are the best may to evolve reusable API within and Angular app.<\/p>\n\n\n\n Overview:<\/strong><\/p>\n\n\n\n Sources:<\/strong> When you create a directive, it can be used as an attribute, element or class name. To define which way to use, you need to set the restrict option in your directive declaration.<\/p>\n\n\n\n The restrict option is typically set to:<\/p>\n\n\n\n \u2018A\u2019 \u2013 only matches attribute name \u2018E\u2019 \u2013 only matches element name These restrictions can all be combined as needed:<\/p>\n\n\n\n \u2018AEC\u2019 \u2013 matches either attribute or element or class name<\/p>\n\n\n\n For more information, feel free to check out the AngularJS documentation<\/a>.<\/p>\n\n\n\n Use an element when you are creating a component that is in control of the template. Use an attribute when you are decorating an existing element with new functionality.<\/p>\n\n\n\n This topic is important as it gauges whether developers understand how a directive can be used inside a view and when to use each way.<\/p>\n\n\n\n Source:<\/strong> https:\/\/docs.angularjs.org\/api\/ng\/service\/$compile#directive-definition-object<\/a><\/p>\n\n\n\n To reset a To disable Scope is an object that refers to the application model. It is an execution context for expressions. Scopes are arranged in a hierarchical structure which mimics the DOM structure of the application. Scopes can watch expressions and propagate events. Scopes are objects that refer to the model. They act as glue between controller and view.<\/p>\n\n\n\n This question is important as it will judge a developer\u2019s knowledge about a Source:<\/strong> https:\/\/docs.angularjs.org\/guide\/scope<\/a><\/p>\n\n\n\n Directives are markers on a DOM element (such as an attribute, element name, comment or CSS class) that tell AngularJS\u2019s HTML compiler ($compile) to attach a specified behavior to that DOM element (e.g. via event listeners), or even to transform the DOM element and its children. <\/p>\n\n\n\n Angular comes with a set of these directives built-in, like ngBind, ngModel, and ngClass. Much like you create controllers and services, you can create your own directives for Angular to use. When Angular bootstraps your application, the HTML compiler traverses the DOM matching directives against the DOM elements.<\/p>\n\n\n\n This question is important because directives define the UI while defining a single-page app. Candidates need to be very clear about creating a new custom directive or using existing ones already pre-build in AngularJS.<\/p>\n\n\n\n Source:<\/strong> https:\/\/docs.angularjs.org\/guide\/directive<\/a><\/p>\n\n\n\n DDO is an object used while creating a custom directive. A standard DDO object has the following parameters:<\/p>\n\n\n\n Angular interview questions like this one mainly judge whether the candidate knows about creating custom directives.<\/p>\n\n\n\n Read more at https:\/\/docs.angularjs.org\/guide\/directive<\/a><\/p>\n\n\n\n Singleton pattern Is a great pattern that restricts the use of a class more than once. We can find a singleton pattern in Angular in dependency injection and the services.<\/p>\n\n\n\n In a sense, if the candidate does 2 times \u2018 Source:<\/strong> http:\/\/joelhooks.com\/blog\/2013\/05\/01\/when-is-a-singleton-not-a-singleton\/<\/a><\/p>\n\n\n\n An interceptor is a middleware code where all the The interceptor is a factory that is registered in Source:<\/strong> https:\/\/docs.angularjs.org\/api\/ng\/service\/$http<\/a><\/p>\n\n\n\n The candidate should use the compile function. The compile function gives access to the directive\u2019s template before transclusion occurs and templates are transformed, so changes can safely be made to DOM elements. This is very useful for cases where the DOM needs to be constructed based on runtime directive parameters.<\/p>\n\n\n\n
\u26a1\ufe0f Identify top applicants from our network of 350,000+
\u26a1\ufe0f Hire 4x faster with vetted candidates (qualified and interview-ready)<\/em><\/p>\n\n\n\n1. What are the basic steps to unit test an AngularJS filter?<\/h2>\n\n\n\n
$filter('yourFilterName')<\/code>.<\/li>
https:\/\/github.com\/daniellmb\/angular-test-patterns\/blob\/master\/patterns\/filter.md<\/a>
https:\/\/docs.angularjs.org\/guide\/unit-testing<\/a><\/p>\n\n\n\n2. What should be the maximum number of concurrent \u201cwatches\u201d? Bonus: How would you keep an eye on that number?<\/h2>\n\n\n\n
ng-stats<\/code>\u00a0can help track your watch count and digest cycles.<\/p>\n\n\n\nng-stats<\/code> gives developers insight into the number of watches Angular is managing, as well as the frequency and duration of digest cycles over time.<\/p>\n\n\n\n
https:\/\/github.com\/kentcdodds\/ng-stats<\/a>
http:\/\/jankfree.org<\/a><\/p>\n\n\n\n3. How do you share data between controllers?<\/h2>\n\n\n\n
events<\/code>
\u2013 Using $parent<\/code>, nextSibling<\/code>, controllerAs<\/code>, etc. to directly access the controllers
\u2013 Using the $rootScope<\/code> to add the data on (not a good practice)<\/p>\n\n\n\n4. What is the difference between
ng-show<\/code>\/ng-hide<\/code> and ng-if<\/code> directives?<\/h2>\n\n\n\nng-show<\/code>\/ng-hide<\/code> will always insert the DOM element, but will display\/hide it based on the condition. ng-if<\/code> will not insert the DOM element until the condition is not fulfilled.<\/p>\n\n\n\nng-if<\/code> is better when we needed the DOM to be loaded conditionally, as it will help load the page a bit faster compared to ng-show<\/code>\/ng-hide<\/code>.<\/p>\n\n\n\n5. What is a digest cycle in AngularJS?<\/h2>\n\n\n\n
$apply()<\/code> if we want to trigger the digest cycle manually.<\/p>\n\n\n\n
\n\n\n\n
Book a session with our interview prep tutors<\/a> today! Your first 15 minutes are free.<\/strong><\/p>\n\n\n\n\n
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\n\n\n\n6. Where should we implement the DOM manipulation in AngularJS?<\/h2>\n\n\n\n
7. Is it a good or bad practice to use AngularJS together with jQuery?<\/h2>\n\n\n\n
8. If you were to migrate from Angular 1.4 to Angular 1.5, what is the main thing that would need refactoring?<\/h2>\n\n\n\n
.directive<\/code> to .component<\/code> to adapt to the new Angular 1.5 components.<\/p>\n\n\n\n9. How would you specify that a scope variable should have one-time binding only?<\/h2>\n\n\n\n
::<\/code>\u201d in front of it. This allows you to check if the candidate is aware of the available variable bindings in AngularJS.<\/p>\n\n\n\n10. What is the difference between one-way binding and two-way binding?<\/h2>\n\n\n\n
11. Explain how
$scope.$apply()<\/code> works<\/h2>\n\n\n\n$scope.$apply<\/code> re-evaluates all the declared ng-models and applies the change to any that have been altered (i.e. assigned to a new value) Explanation: $scope.$apply()<\/code> is one of the core angular functions that should never be used explicitly, it forces the angular engine to run on all the watched variables and all external variables and apply the changes to their values.<\/p>\n\n\n\n12. What directive would you use to hide elements from the HTML DOM by removing them from that DOM without changing their styling?<\/h2>\n\n\n\n
ngIf<\/code> directive, when applied to an element, will remove that element from the DOM if its condition is false.<\/p>\n\n\n\n13. What makes the
angular.copy()<\/code> method so powerful?<\/h2>\n\n\n\n
https:\/\/docs.angularjs.org\/api\/ng\/function\/angular.copy<\/a>
https:\/\/en.wikipedia.org\/wiki\/Object_copying<\/a><\/p>\n\n\n\n14. How would you make an Angular service return a promise? Write a code snippet as an example<\/h2>\n\n\n\n
angular.factory('testService', function<\/strong>($q) {\n return<\/strong> {\n getName: function<\/strong>() {\n var<\/strong> deferred = $q.defer();\n\n \/\/API call here that returns data<\/em>\n testAPI.getName().then(function<\/strong>(name) {\n deferred.resolve(name);\n });\n\n return<\/strong> deferred.promise;\n }\n };\n});<\/code><\/pre>\n\n\n\n$q<\/code> library is a helper provider that implements promises and deferred objects to enable asynchronous functionality.<\/p>\n\n\n\n15. What is the role of services in AngularJS and name any services made available by default<\/h2>\n\n\n\n
$http<\/code> service: The $http service is a core Angular service that facilitates communication with the remote HTTP servers via the browser\u2019s XMLHttpRequest object or via JSONP<\/li>$log<\/code> service: Simple service for logging. Default implementation safely writes the message into the browser\u2019s console<\/li>$anchorScroll<\/code>: it scrolls to the element related to the specified hash or (if omitted) to the current value of $location.hash() Why should one know about AngularJS Services, you may ask. Well, understanding the purpose of AngularJS Services helps bring modularity to AngularJS code<\/li><\/ul>\n\n\n\nservice()<\/code> method or the factory()<\/code> method.<\/li>
https:\/\/docs.angularjs.org\/guide\/services<\/a>
http:\/\/www.tutorialspoint.com\/angularjs\/angularjs_services.htm<\/a><\/p>\n\n\n\n![\"\"](\"https:\/\/arc.dev\/developer-blog\/wp-content\/uploads\/2022\/02\/Meet-HireAI-blog-CTA-banner-1024x256.png\")
<\/a><\/figure>\n\n\n\n16. When creating a directive, it can be used in several different ways in the view. Which ways for using a directive do you know? How do you define the way your directive will be used?<\/h2>\n\n\n\n
\u2018C\u2019 \u2013 only matches class name<\/p>\n\n\n\n17. When should you use an attribute versus an element?<\/h2>\n\n\n\n
18. How do you reset a
$timeout<\/code>, $interval()<\/code>, and disable a $watch()<\/code>?<\/h2>\n\n\n\ntimeout<\/code> and\/or $interval<\/code>, assign the result of the function to a variable and then call the .cancel()<\/code> function:<\/p>\n\n\n\nvar<\/strong> customTimeout = $timeout(function<\/strong>() {\n \/\/ arbitrary code<\/em>\n}, 55);\n\n$timeout.cancel(customTimeout);\n<\/code><\/pre>\n\n\n\n$watch()<\/code>, we call its deregistration function. $watch()<\/code> then returns a deregistration function that we store to a variable and that will be called for cleanup:<\/p>\n\n\n\nvar<\/strong> deregisterWatchFn = $scope.$on('$destroy', function<\/strong>() {\n \/\/ we invoke that deregistration function, to disable the watch<\/em>\n deregisterWatchFn();\n});\n<\/code><\/pre>\n\n\n\n19. Explain what is a
$scope<\/code> in AngularJS.<\/h2>\n\n\n\n$scope<\/code> object, and it is one of the most important concepts in AngularJS. Scope acts like a bridge between view and model.<\/p>\n\n\n\n20. What are Directives?<\/h2>\n\n\n\n
21. What is DDO Directive Definition Object?<\/h2>\n\n\n\n
var<\/strong> directiveDefinitionObject = {\n priority: 0,\n template: '<div><\/div>', \/\/ or \/\/ function(tElement, tAttrs) { ... },<\/em>\n \/\/ or<\/em>\n \/\/ templateUrl: 'directive.html', \/\/ or \/\/ function(tElement, tAttrs) { ... },<\/em>\n transclude: false,\n restrict: 'A',\n templateNamespace: 'html',\n scope: false,\n controller: function<\/strong>(\n $scope,\n $element,\n $attrs,\n $transclude,\n otherInjectables\n ) { ... },\n controllerAs: 'stringIdentifier',\n bindToController: false,\n require: 'siblingDirectiveName', \/\/ or \/\/ ['^parentDirectiveName', '?optionalDirectiveName', '?^optionalParent'],<\/em>\n compile: function<\/strong> compile<\/strong>(tElement, tAttrs, transclude) {\n return<\/strong> {\n pre: function<\/strong> preLink<\/strong>(scope, iElement, iAttrs, controller) { ... },\n post: function<\/strong> postLink<\/strong>(scope, iElement, iAttrs, controller) { ... }\n };\n \/\/ or<\/em>\n \/\/ return function postLink( ... ) { ... }<\/em>\n }\n \/\/ or<\/em>\n \/\/ link: {<\/em>\n \/\/ pre: function preLink(scope, iElement, iAttrs, controller) { ... },<\/em>\n \/\/ post: function postLink(scope, iElement, iAttrs, controller) { ... }<\/em>\n \/\/ }<\/em>\n \/\/ or<\/em>\n \/\/ link: function postLink( ... ) { ... }<\/em>\n};\n<\/code><\/pre>\n\n\n\n22. What is a singleton pattern and where we can find it in AngularJS?<\/h2>\n\n\n\n
new Object()<\/code>\u2018 without this pattern, the candidate will be allocating 2 pieces of memory for the same object. With a singleton pattern, if the object exists, it’ll be reused.<\/p>\n\n\n\n23. What is an interceptor? What are common uses of it?<\/h2>\n\n\n\n
$http<\/code> requests go through.<\/p>\n\n\n\n$httpProvider<\/code>. There are 2 types of requests that go through the interceptor, request and response (with requestError<\/code> and responseError<\/code> respectively). This piece of code is very useful for error handling, authentication, or middleware in all the requests\/responses.<\/p>\n\n\n\n24. How would you programmatically change or adapt the template of a directive before it is executed and transformed?<\/h2>\n\n\n\n