Cognizant Angular Frontend Developer Interview Questions and Answers

Fetch data from an API and display it in Angular, using a custom pipe to format IDs.

• Use HttpClient to make API calls: `this.http.get(apiUrl).subscribe(data => this.data = data);`

• Create a custom pipe using Angular CLI: `ng generate pipe idFormatter`.

• In the pipe, implement `transform(value: number): string` to convert ID to 1**8 format.

• Use the pipe in the template: `{{ id | idFormatter }}` to display formatted IDs.

Challenges faced during Angular migration, creating reducers in ngrx, flattening arrays, and sorting.

• Challenges during migration: compatibility issues, deprecated features, breaking changes.

• Creating reducers in ngrx: define actions, create reducer function, update state immutably.

• Flattening arrays: use flat() method, recursion, or spread operator.

• Sorting arrays: use sort() method with custom comparator function.

Pipes in Angular are used for transforming data in templates.

• Pipes are used to format data before displaying it in the view.

• Angular provides built-in pipes like DatePipe, UpperCasePipe, LowerCasePipe, etc.

• Custom pipes can also be created for specific formatting needs.

• Pipes can be chained together for complex transformations.

• Example: {{ birthday | date:'dd/MM/yyyy' }} will format the birthday date.

Closure in JavaScript allows a function to access variables from its outer scope even after the function has finished executing.

• Closure is created when a function is defined within another function and the inner function references variables from the outer function.

• The inner function maintains a reference to the outer function's scope even after the outer function has finished executing.

• Closures are commonly used in ev...read more

A directive in Angular is a class with a @Directive decorator that allows you to attach behavior to elements in the DOM.

• Directives are used to manipulate the DOM in Angular applications.

• There are three types of directives in Angular: component, structural, and attribute directives.

• Examples of directives include ngIf, ngFor, and ngStyle.

Migrating Angular versions involves planning, updating dependencies, and testing for compatibility issues.

• 1. Review Angular's official update guide for version-specific instructions.

• 2. Update Angular CLI globally using: npm install -g @angular/cli@latest.

• 3. Update local project dependencies using: ng update @angular/core @angular/cli.

• 4. Check for deprecated APIs and replace them with recommended alternatives.

• 5. Run uni...read more