Test your knowledge of closures, async/await, prototypes, and the event loop.

Master core JavaScript concepts through hands-on practice. This quiz covers essential topics including closures, the event loop, prototypes, async programming, and type coercion. Perfect for interview preparation and solidifying your understanding of JavaScript fundamentals.

What is the output of `console.log(typeof NaN)`?

What will `console.log([] == false)` output?

What is the output of `console.log(1 + '2' + 3)`?

What is the difference between `let` and `var`?

What is the output of `console.log(typeof null)`?

What does `this` refer to in an arrow function?

What is the spread operator (...) used for?

What is the difference between `null` and `undefined`?

What does `Array.prototype.map()` return?

JavaScript Mastery Quiz

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