Blackhawk Network Interview Questions, Process, and Tips

Hoisting is a JavaScript mechanism where variables and function declarations are moved to the top of their scope.

• Variables declared with var are hoisted to the top of their scope

• Function declarations are hoisted before variables

• Function expressions are not hoisted

• Hoisting can lead to unexpected behavior and bugs

Cookies are used to store user data and preferences on websites for a better browsing experience.

• Cookies help websites remember user login information

• They can also store user preferences such as language and currency settings

• Cookies are used for tracking user behavior and serving targeted ads

• They can also be used for website analytics to improve user experience

• Cookies can be both first-party (set by the website being v...read more

Autowired is used in Spring Framework to automatically inject dependencies into a bean.

• Autowired is used to reduce the amount of boilerplate code required for dependency injection.

• It allows for automatic wiring of dependencies based on type or name.

• Autowired can be used in constructors, fields, or setter methods.

• Example: @Autowired private UserService userService;

• Example: @Autowired public UserController(UserService us

To create a thread safe singleton, use double-checked locking or static initialization.

• Use a private constructor to prevent direct instantiation.

• Create a private static instance of the class.

• Use double-checked locking or static initialization to ensure thread safety.

• Provide a public static method to access the instance.

Lazy loading defers loading of non-critical resources until needed, while eager loading loads all resources upfront.

• Lazy loading improves initial page load time and reduces unnecessary resource usage.

• Eager loading is useful for small applications or when all resources are critical.

• Examples of lazy loading include images, videos, and large data sets.

• Examples of eager loading include small CSS and JavaScript files.

Classes in JavaScript are a way to create reusable code templates for objects.

• Classes are declared using the 'class' keyword.

• They can have constructors, methods, and properties.

• Instances of a class are created using the 'new' keyword.

• Classes can also be extended using the 'extends' keyword.

• Classes can be used to create objects with similar behavior and properties.