Interview questions JS - Habilya/LearningCourseNotes GitHub Wiki

JS whats the difference between var let const?

In JavaScript, var, let, and const are used to declare variables, but they have some key differences:

  1. var: Variables declared with var are function-scoped or globally scoped, but not block-scoped. This means that var variables can be accessed and modified outside of the function in which they are defined. This can lead to potential bugs and unexpected behavior.

  2. let: Variables declared with let are block-scoped, which means they are only accessible within the block they are defined in (such as a loop or an if statement). This helps to prevent bugs and unexpected behavior that can arise from using var.

  3. const: Variables declared with const are also block-scoped like let, but they are also immutable. This means that once a value is assigned to a const variable, it cannot be changed or reassigned. This is useful when you want to ensure that a variable remains constant and does not change throughout your program.

In general, it is recommended to use const whenever possible to ensure immutability and prevent accidental reassignment of variables, and to use let for variables that need to be reassigned within a block scope. Avoid using var as it can lead to confusing and error-prone behavior.

what are the closures and premises in front end development?

Answer:

In front-end development, closures and premises are related 
concepts that are used in programming to help create a modular and efficient codebase.

Closures refer to the ability of functions to "remember" the environment in which they were created, 
including all variables and functions that were within their scope at the time of creation. 
This allows functions to maintain access to those variables and functions even after they have been executed, 
providing a way to encapsulate and control the flow of data within a program.

Premises, on the other hand, are the foundational assumptions or principles that guide the development of a project. 
In front-end development, premises may include design principles, user experience considerations, 
and performance benchmarks that inform the decisions made during the development process. 
By establishing clear premises at the outset of a project, 
developers can ensure that their code is well-structured and aligned with the goals of the project.

Both closures and premises play important roles in front-end development, 
helping to create efficient and maintainable code that meets the needs of users and stakeholders. 
By understanding these concepts and incorporating them into their development practices, 
front-end developers can create high-quality, responsive, and user-friendly websites and applications.