36 practice questions with answers for MEAN Stack interviews in Indore.
MEAN Stack jobs in Indore
Indore is one of central India's fastest-growing IT hubs, with IT-services campuses and product start-ups in its Super Corridor and IT parks. Companies here hire many freshers and value hands-on project work.
Below are 36 questions that match the mix of service, product and domain employers hiring mean stack developers in Indore.
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01
Write a custom validator that rejects passwords without a number and an uppercase letter.
Check how many queries populate triggers and how much data each returns. Select only needed fields in populate, use lean(), and add indexes on the referenced fields. If the list always needs a customer name, store it with the extended reference pattern to avoid the join entirely. For complex filtering on related data, switch to one aggregation with $lookup and $project, and paginate.
03
What are generics in TypeScript? Give an Angular-related example.
Generics let you write reusable code that works with many types while keeping type safety, using type parameters like T. For example, an ApiResponse<T> interface can wrap any payload, and a service method get<T>(url: string): Observable<T> returns correctly typed data. Angular's HttpClient.get<User[]>() uses generics so the component knows it receives an array of users, without casting.
04
After deploying the Angular app behind a load balancer, navigating directly to /orders/42 gives a 404. What is wrong?
The Angular router handles that path in the browser, but the web server looks for a real file at /orders/42 and finds none. Configure the server to return index.html for unknown routes: try_files $uri $uri/ /index.html in Nginx, a rewrite rule in IIS or static hosting, or a catch-all route in Express that serves the built index.html after API routes. Alternatively use server-side rendering.
Define a TypeScript interface for the document, then create a Schema typed with that interface and a model with model<IUser>('User', userSchema). Mongoose infers types for queries, so findById returns a typed document. For lean queries, results are plain typed objects. Schema options like timestamps add createdAt and updatedAt, and you can type instance methods, statics and virtuals through additional generic parameters.
06
What is a route resolver and when would you use one?
A resolver fetches data before a route activates, so the component receives ready data instead of showing an empty state first. A functional resolver, ResolveFn<Product>, uses inject() to call a service and returns an Observable or Promise. The data is available through ActivatedRoute or bound inputs. Use it for detail pages that are useless without data, but avoid it for slow calls, because navigation waits.
07
Show the tsconfig settings you would enable for a strict Node.js Express API.
ngOnChanges runs when input values change. ngOnInit runs once after the first inputs are set, used for initial data loading. ngDoCheck allows custom change detection. ngAfterContentInit and ngAfterViewInit run after projected content and the view are ready, used for DOM access. ngOnDestroy runs before removal, used for cleanup. With signals, effect, computed and DestroyRef often replace several of these hooks.
09
What is the role of a controller-service-repository structure in an Express API?
Controllers handle HTTP: they read request data, call services and format responses with status codes. Services contain business rules, such as checking stock before creating an order, and are independent of Express. Repositories or models encapsulate database access through Mongoose. This separation makes code easier to test, lets you reuse services in jobs or other transports, and stops route files from turning into large unmaintainable blocks.
10
Write an Nginx server block that serves Angular and proxies /api to Node.
Explain that any hides real bugs and removes autocompletion, then show concrete fixes: proper interfaces for API models, unknown with narrowing for untrusted data, and generics for reusable helpers. Enable the noImplicitAny compiler option and the ESLint no-explicit-any rule as a warning, fix the most critical files first, and add a review guideline. Keep the conversation constructive by pairing on one module together.
12
An API sometimes returns null for a nested field and the Angular app crashes with cannot read properties of undefined. How do you fix it properly?
Model the API response accurately in TypeScript, marking the field as optional or nullable, and keep strictNullChecks on so the compiler forces you to handle it. Use optional chaining in code and templates, provide defaults with ??, and show a fallback in the UI with @if. Also agree with the backend team on the contract, and validate responses at the boundary if the data is untrusted.
13
Write an aggregation that finds the top five customers by total spend with their names.
A signal is a reactive value container: you read it by calling it, count(), and update it with set or update. Angular tracks which templates, computed values and effects read a signal, so when it changes only dependent parts update. Signals give fine-grained reactivity, enable zoneless change detection and are simpler than RxJS for synchronous component state. They are stable and central to modern Angular.
15
How does lazy loading work with the Angular router?
Lazy loading defers downloading a feature's code until the user navigates to it. Use loadComponent: () => import('./admin/admin.component').then(m => m.AdminComponent) for a single component, or loadChildren to load a file of child routes. The CLI builds a separate chunk for each lazy route. You can add preloading strategies like withPreloading(PreloadAllModules) to fetch lazy chunks in the background after startup.
16
What are directives in Angular and what types exist?
Directives add behaviour to elements. Components are directives with templates. Attribute directives change appearance or behaviour of an existing element, such as ngClass, ngStyle or a custom appHighlight using host bindings. Structural directives change the DOM layout by adding or removing elements, like the older *ngIf and *ngFor, now largely replaced by built-in control flow. Custom directives keep repeated DOM logic out of components.
17
Users complain that the app shows a blank screen whenever the backend is down. How do you improve this?
Add a global error interceptor that maps network and 5xx errors to a friendly toast or banner, with retry for transient failures. In each data component, handle loading, error and empty states explicitly, using httpResource status signals or catchError with fallback values. Show a retry button, keep cached data visible if available, and log errors to monitoring. A health check banner helps during outages.
18
A product list with 2,000 rows re-renders slowly whenever any data changes. How do you optimise it?
Use @for with a proper track expression, such as track product._id, so Angular reuses DOM nodes instead of recreating them. Switch the component to OnPush and update data immutably or with signals. Replace function calls in templates with computed signals or pure pipes. For very long lists, use virtual scrolling from the Angular CDK and paginate on the server.
19
Users double-click the Pay button and two payment requests are sent. How would you prevent it on the frontend?
Disable the button while the request is pending, using an isSubmitting signal. In RxJS, model clicks as a stream and use exhaustMap, which ignores new clicks until the current payment request completes. Show a loading state and handle errors so the button re-enables. The backend must still use idempotency keys, because frontend protection alone cannot stop network retries or duplicate tabs.
20
You need a dropdown value that can only be 'pending', 'shipped' or 'delivered'. How do you model it so invalid values are impossible?
Use a string literal union, type OrderStatus = 'pending' | 'shipped' | 'delivered', or a const array with as const and derive the type from it, so the list can also render the dropdown options. Type the component property and API model with OrderStatus. The compiler then rejects typos like 'shiped'. On the backend, mirror the same values with a Mongoose enum validator.
21
An Express endpoint generates a large PDF report and the whole API slows down while it runs. How do you fix it?
PDF generation is CPU-heavy and blocks the event loop. Move it to a background job: the endpoint creates a job in a queue such as BullMQ with Redis and immediately returns 202 Accepted with a job id. A separate worker generates the PDF, uploads it to storage and updates the job status. Angular polls the status or receives a websocket notification, then downloads the file.
22
How do you design REST endpoints for a resource like orders, including nested data?
Use plural nouns and HTTP methods: GET /orders, GET /orders/:id, POST /orders, PATCH /orders/:id and DELETE /orders/:id. For related data, use shallow nesting like GET /users/:id/orders. Express actions that are not CRUD as sub-resources or clear verbs, such as POST /orders/:id/cancel. Support filtering, sorting and pagination with query parameters, return proper status codes and document the API with OpenAPI.
23
What is the difference between template-driven and reactive forms in Angular?
Template-driven forms build the form model from directives in the template, mainly ngModel, and suit small, simple forms. Reactive forms define the model explicitly in the component with FormControl, FormGroup and FormArray, giving synchronous access, strong typing, easier dynamic fields, observable valueChanges and simpler unit testing. Most enterprise Angular applications use reactive forms for complex or validated forms.
24
An Angular page needs to show different content for admin and normal users. How would you implement it in the template?
Expose the current user's role from an auth service as a signal and read it in the component with a computed value such as isAdmin. In the template, use @if (isAdmin()) to render admin sections and @else for the normal view, or create a small structural directive for permission checks if this repeats. Remember to also protect routes with guards and enforce permissions on the Express API.
25
Serve the built Angular app and the API from one Express server.
Interceptors sit between HttpClient and the server and can modify every request and response. Modern Angular uses functional interceptors of type HttpInterceptorFn registered through withInterceptors. Common uses are attaching an Authorization header, adding a base URL, showing a global loading indicator, logging, retrying failed requests, refreshing expired tokens and mapping errors to user-friendly messages. Interceptors run in the order they are listed.
28
What is a service in Angular and why should business logic live there?
A service is a class, usually decorated with @Injectable, that holds logic or data not tied to a single view, such as API calls, authentication, caching or shared state. Keeping this out of components makes components thin and focused on presentation, lets several components share the same data, and makes logic easy to unit test by injecting mock services. Services are created and supplied by Angular's dependency injection system.
29
After a new release, a bug affects many users. How do you respond and prevent a repeat?
First limit the impact: roll back to the previous version or disable the feature with a flag, and communicate status to support. Then reproduce the bug, fix it with a test that covers the case, and redeploy through the normal pipeline. Afterwards, run a blameless post-mortem to find gaps, such as missing tests, review or monitoring, and add the actions to the backlog.
30
Walk me through the MEAN project you are most proud of.
Situation: for my final-year project I built a hospital appointment system. Task: let patients book slots and doctors manage schedules. Action: I designed MongoDB collections with indexes for slots, built a TypeScript Express API with JWT and role checks, and an Angular frontend with reactive forms, guards and signals. I added tests and deployed with Docker on a cloud VM. Result: our college clinic used it for a semester.
31
Write an injectable service that fetches and caches a list of categories.
Send a FormData body with HttpClient post and options reportProgress: true and observe: 'events'. Filter the event stream for HttpEventType.UploadProgress to calculate percent from loaded and total, and for HttpEventType.Response to get the final result. Show a progress bar bound to a signal, allow cancelling by unsubscribing, and validate size and type before upload. For very large files, upload directly to storage with pre-signed URLs.
33
How should HTTP errors be handled in an Angular application?
Handle them at two levels. A global error interceptor catches HttpErrorResponse, redirects to login on 401, shows a toast for 500 errors and logs details. Component or service code uses catchError to provide fallbacks or show specific messages, such as field errors from a 422 response. Use retry with a delay for transient network failures, and never leave errors unhandled so the UI shows a blank state.
34
How do you serve an Angular build and an Express API from the same Node server?
Build Angular with ng build, which outputs static files to dist/project/browser. In Express, register API routes under /api first, then serve the static files with express.static, and finally add a catch-all GET route that returns index.html so Angular routing works on refresh. In larger deployments, Nginx or a CDN usually serves the Angular files while Express handles only the API.
Narrowing is TypeScript refining a broad type to a more specific one inside a code block based on checks. typeof, instanceof, the in operator, equality checks and discriminated union tags all narrow types. A custom type guard is a function returning a predicate like value is Admin, which tells the compiler the type after the check. This makes handling union types, such as API success or error responses, safe.
36
Write a zod validation middleware for an Express route in TypeScript.
Which companies hire MEAN Stack professionals in Indore?
Companies with large offices in Indore include many IT services and product firms. Use their company pages below to practise employer-specific sets.
Are MEAN Stack interviews in Indore different from other cities?
The questions depend more on the company than the city. Indore's mix of employers decides the style: Companies here hire many freshers and value hands-on project work
How do I find MEAN Stack jobs in Indore?
Shortlist companies with Indore offices, keep your CV focused on MEAN Stack projects, apply on company career pages and job portals with the Indore filter, and practise the questions on this page before each interview.