Question of the Day #17 [Talk::Overflow]

This post explains a quiz originally shared as a LinkedIn poll . 🔹 The Question let count = 0 ; function increment () { count ++ ; var count ; return count ; } console . log ( increment ()); console . log ( count ); Hint: Think about where var declarations end up before any code runs — and what happens when you increment something that doesn't have a value yet. Follow me for JavaScript puzzles and weekly curations of developer talks & insights at Talk::Overflow: https://talkoverflow.substack.com/ 🔹 Solution Correct answer: B) NaN, 0 The first console.log prints NaN . The second prints 0 . 🧠 How this works This quiz targets a subtle but dangerous interaction between var hoisting and variable shadowing. When JavaScript parses the increment function, the var count; declaration is hoisted to the top of the function scope — even though it appears after count++ in the source code. This creates a local count variable inside increment , completely separate from the outer let count = 0 . At run