js_flashcards_other

Question 1

How are function declarations hoisted?

Answer 1

Fully hoisted: name and body available before definition. Can be called before declaration.

Question 2

Why avoid deeply nested logic?

Answer 2

Reduces readability and complexity. Avoid by breaking functions down and using early returns.

Question 3

What is the Single Responsibility Principle (SRP)?

Answer 3

A function should have one responsibility and one reason to change. Makes code modular and testable.

Question 4

Advantages of arrow functions?

Answer 4

Concise syntax and lexical this binding to avoid context issues.

Question 5

What are template literals?

Answer 5

Strings using backticks with interpolation and multiline support.

Question 6

What is modular code and why important?

Answer 6

Organized, reusable units. Improves reusability, maintainability, and testing.

Question 7

How does inline caching work?

Answer 7

Stores property lookup results for reuse, avoiding repeated lookups.

Question 8

Impact of hidden classes on performance?

Answer 8

Optimize property access if objects share shape. Different shapes reduce performance.

Question 9

What are the 7 primitive data types?

Answer 9

string, number, boolean, null, undefined, symbol, bigint.

Question 10

What are reference types?

Answer 10

Objects, arrays, functions. Complex structures stored by reference.

Question 11

Explain copy by value in JS.

Answer 11

Primitives copied independently. Changes do not affect the copy.

Question 12

Explain copy by reference in JS.

Answer 12

References copied. Both point to same object. Changes affect all references.

Question 13

Difference between == and ===?

Answer 13

== compares after type conversion.
=== compares without conversion. Prefer ===.

Question 14

typeof null result?

Answer 14

typeof null === ‘object’ (historical bug).

Question 15

Explain reference counting GC.

Answer 15

Counts references. When zero, object reclaimed. Fails with circular refs.

Question 16

Purpose of nullifying references?

Answer 16

Set to null to signal GC object no longer needed.

Question 17

Why avoid unnecessary objects?

Answer 17

Too many temps strain GC. Reuse objects when possible.

Question 18

What is an object pool?

Answer 18

Reuse pre-initialized objects to reduce GC overhead.