Which of these values are falsy in JavaScript? (Select all that apply.)

A string containing the word false

Which statement about `let` and `var` is correct?

let is block-scoped; var is function-scoped

var is block-scoped; let is global

let variables are always constant

What does `JSON.parse()` do with a valid JSON string?

Converts it into a JavaScript value/object

Converts an object into a string

JavaScript Fundamentals Quiz

Think you really know JavaScript? This quick quiz checks your grasp of the core concepts every JS developer leans on — types, scope, arrays, coercion, and a few classic gotchas.

12 multiple-choice questions, each with an explanation after you answer, so you actually learn as you go. Great as a self-check, a classroom warm-up, or a lightweight skills screen.

Colorful JavaScript source code on a dark screen