Getting Started: JavaScript Interview Questions

JavaScript interviews for junior roles often focus heavily on the language’s unique quirks, and failing to understand core mechanics like type coercion or scope is a common reason candidates struggle during technical screens. This course covers the exact concepts you need to confidently answer these questions, starting from first principles. You will begin with the type system, exploring primitives, typeof, type coercion, equality comparisons, and the specific behaviors of null, undefined, and NaN. From there, the course moves into variables and scope, explaining the practical differences between var, let, and const, alongside notoriously tricky interview topics like hoisting, the temporal dead zone, and shadowing. You will also look at operators and expressions, covering logical short-circuiting, nullish coalescing, optional chaining, and how to properly use spread and rest operators, before moving into string manipulation, number conversion, and parsing.

Once the basics are covered, the course examines how JavaScript handles data structures and functions. You will learn about reference semantics, destructuring, and iteration for both objects and arrays, including the specific mutation behaviors of methods like sort and slice. Next, you will examine functions in detail, comparing declarations, expressions, and arrow functions, before tackling the most common interview hurdles: closures, execution context, and the rules of this binding, including how to manipulate it with call, apply, and bind. The curriculum then transitions into object-oriented patterns, explaining the prototype chain, classes, and inheritance using extends and super. Finally, you will learn the mechanics of asynchronous JavaScript, from callbacks and the event loop to promises, async / await, and the exact difference between microtasks and macrotasks, rounding out the course with modern built-ins like Map, Set, generators, and module syntax.