Question 1

How do you approach hoisting questions in an interview?

Accepted Answer

Walk through the memory phase first: what is hoisted and to what value (undefined for var, full body for function declarations, TDZ for let/const). Then walk the execution phase line-by-line to determine each output.

Question 2

What does console.log(a) print if var a = 5 is below it?

Accepted Answer

undefined. The var declaration is hoisted and initialized to undefined. The assignment a = 5 runs only when the line is reached, so the earlier log sees undefined.

Question 3

What happens when you call a function expression before its assignment?

Accepted Answer

TypeError: x is not a function. The var variable is hoisted with undefined, so calling it as a function fails. Only function declarations are hoisted with their body.

Question 4

Does typeof escape the Temporal Dead Zone?

Accepted Answer

No. typeof on a let or const variable in the TDZ throws ReferenceError. typeof on a var that has not been assigned returns the string 'undefined' without throwing.

How do you approach hoisting questions in an interview?

More FAQs in Common Hoisting Interview Questions in JavaScript

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