1. What is the difference between var, let, and const?

Ans:

• var can change value, is function scoped, and you can use it before declaring (hoisting).
• let can change value, is block scoped, and cannot be used before declaring.
• const cannot change value, is block scoped, and cannot be used before declaring.

2. What is the spread operator (...)?

Ans:

• Spread operator ... is used to copy items from an array or object. It can also be used to combine arrays or objects into a new one. It helps to avoid changing the original array or object.

3. What is the difference between map(), filter(), and forEach()?

Ans:

• forEach() goes through each item but does not return anything.
• map() goes through each item and makes a new array with changed values.
• filter() goes through each item and makes a new array with only items that pass a test.

4. What is an arrow function?

Ans:

• Arrow function is a short way to write a function in JS. It uses => and is cleaner than the regular function keyword. It also keeps this value from outside the function.

5. What are template literals?

Ans:

• Template literals are strings written with backticks ```` instead of quotes. They allow embedding expressions using ${} inside the string. They also support multi-line strings without extra characters.