Test Your JavaScript Knowledge

Lydia Hallie

Lydia Hallie

Lydia Hallie
2 hours, 11 minutes CC
Test Your JavaScript Knowledge

Course Description

Challenge your core knowledge of JavaScript with 50 interactive quiz questions covering topics like the event loop, scopes and closures, the "this" keyword, classes and prototypes, garbage collection, and more! After each question, you'll get an in-depth visual explanation from Lydia to deepen your understanding of fundamental JavaScript concepts!

This course and others like it are available as part of our Frontend Masters video subscription.


Course Details

Published: February 20, 2024

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Table of Contents


Section Duration: 2 hours, 11 minutes
  • Introduction
    Lydia Hallie introduces a Q&A style workshop where they present 50 questions on various topics in JavaScript, including event loop, closures, classes, prototypes, and miscellaneous content like numbers and weak maps. Students will be given time to answer each question, and Lydia provides detailed explanations for each answer. The course aims to enhance participants' understanding of JavaScript concepts.
  • Event Loop & Task Queue
    Lydia explains the concept of the event loop in JavaScript. They discuss the different components of the event loop, such as the call stack, task queue, and microtask queue. They also provide examples and explanations of how different tasks and callbacks are scheduled and executed in the event loop.
  • Scope & Closure
    Lydia explains the concept of scope and closures in JavaScript. They discuss how closures work by referencing lexical environments and demonstrate examples of closures in code. The instructor also covers topics such as hoisting, variable declaration, and block scope.
  • this keyword
    Lydia explains the behavior of the "this" keyword in JavaScript. They cover various scenarios, including the global context, regular functions, arrow functions, classes, strict mode, event handlers, and the use of call, bind, and apply methods.
  • Classes & Prototypes
    Lydia explains the concept of classes and prototypes in JavaScript. They demonstrate how classes can be extended and how properties and methods can be added to the prototype. They also discuss the difference between properties defined in the constructor and those added to the prototype. The lesson includes examples and explanations of how prototypes work and how they affect memory usage. The instructor also covers topics such as static methods and the use of object.create to create objects with specific prototypes.
  • Generators & Iterators
    Lydia demonstrates how to create a generator function using the asterisk symbol and explains that a generator function returns an iterator object. The instructor also shows how to use the iterator object to call the next method and retrieve the yielded values. They discuss the difference between regular functions and generator functions, highlighting the ability to pause and resume execution with generator functions. Additionally, the instructor explains how to create custom iterable objects in JavaScript by implementing the symbol.iterator method.
  • Garbage Collection
    Lydia discusses various concepts related to garbage collection in JavaScript. They explain how objects are garbage collected based on their availability in the global lexical environment and how references to objects affect their garbage collection. The instructor also explains the concept of weak maps and how they differ from regular maps in terms of garbage collection. They also discuss closures and when inner functions become eligible for garbage collection. The lesson concludes with a discussion on the event loop and how it interacts with garbage collection.
  • Modules
    Lydia discusses different module loading mechanisms such as CommonJS, AMD, UMD, and ESM. They explain the characteristics and use cases of each mechanism, including their support for server-side or client-side usage, synchronous or asynchronous loading, and static analysis and tree shaking capabilities. The instructor also demonstrates the order of logs when using a combination of require and import statements in a script. Finally, they compare the differences between require and import, highlighting their conditional usage, hoisting behavior, synchronous or asynchronous loading, and support for static analysis and tree shaking.
  • Numbers
    Lydia explains the behavior of the post-increment operator and pre-increment operator, as well as the difference between using the "==" and "===" operators. They also discuss the "isNaN" function and the "toString" method for numbers. The lesson concludes with a discussion on the "parseInt" and "parseFloat" functions and how to use the "toString" method with different radix values.
  • Miscellaneous
    Lydia covers various topics including working with maps and sets, freezing objects, using proxies, manipulating arrays, working with default parameters, comparing symbols, and using tagged template literals. The instructor explains the concepts and provides examples to illustrate how they work.
  • Wrapping Up
    Lydia wraps up the course by emphasizing that the goal was to remind students of certain concepts and provide resources for further learning. The instructor also encourages participants to reach out with any additional questions or concerns.
it was nice to get a refresh on my JavaScript Knowledge and I learned a few other tricks!
Jorge Mendoza

Jorge Mendoza


Frontend Masters is consistently helping me level up my skills. Their "Testing Your JavaScript Knowledge!" course by Lydia Hallie was fantastic. I learned a lot about various advanced JS concepts, and the course quiz based approach was super helpful. Definitely recommend!



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