--- title: "JavaScript: Language Fundamentals & Modern Features" lang: "en" author: "Mohammad Abu Mattar" canonical: https://mkabumattar.com/post/javascript-fundamentals-quiz --- [Home](/)›[Quizzes](/quizzes)›[All Categories](/quizzes/categories)›[JavaScript](/quizzes/categories/javascript) Quizzes [Prev in JavaScriptAsync JavaScript: Promises, Async/Await, Event Loop](/quizzes/post/async-javascript-promises-quiz)[Next in JavaScriptReact Fundamentals: Components, Hooks & State Management](/quizzes/post/react-fundamentals-quiz) [JavaScript](/quizzes/categories/javascript)[Programming](/quizzes/categories/programming)[Web Development](/quizzes/categories/web-development)[Frontend](/quizzes/categories/frontend) # JavaScript: Language Fundamentals & Modern Features [Mohammad Abu Mattar](/authors/mohammad-abu-mattar)20 QuestionsIntermediatePublished: 03 Feb 2026 [Markdown for AI(opens in a new tab)](/post/javascript-fundamentals-quiz/index.md "Open the plain-Markdown version of this page, for pasting into an AI tool") Series [Frontend Essentials](/series/frontend-essentials)1/4 [NextTypeScript: Typed JavaScript Fundamentals](/quizzes/post/typescript-fundamentals-quiz) All posts in this series (4) Quizzes4 1. [JavaScript: Language Fundamentals & Modern FeaturesYou are here](/quizzes/post/javascript-fundamentals-quiz) 2. [TypeScript: Typed JavaScript Fundamentals](/quizzes/post/typescript-fundamentals-quiz) 3. [CSS Fundamentals: Selectors, Box Model & Styling](/quizzes/post/css-fundamentals-quiz) 4. [HTML Semantics & Web Accessibility](/quizzes/post/html-semantics-accessibility-quiz) ## JavaScript: Language Fundamentals & Modern Features Up to 20 questions, shuffled on every run Quiz Configuration Enterto start Welcome to the JavaScript Basics Quiz! This quiz tests your understanding of fundamental JavaScript concepts, syntax, and modern programming best practices. Each question is multiple-choice, and you’ll find hints to help you along the way. Good luck! Answer key and explanations20 questions The quiz above draws 20 questions at random from these 30, so a second attempt will not be the same run. Everything in the pool is listed here. 1. Which keyword is used to declare a block-scoped variable that can be reassigned? Answer\`let\` 2. What is the result of "5" + 2 in JavaScript? Answer\`"52"\` 3. How do you create a function using the arrow syntax? Answer\`const my\_func = () => {}\` 4. What does "===" check that "==" does not? AnswerBoth the value and the type 5. Which method is used to write text directly into the browser console? Answer\`console.log()\` 6. What is the purpose of "document.querySelector()" AnswerSelecting an element by CSS 7. Which of these is NOT a valid way to declare a variable in modern JS? Answer\`set\` 8. What is a "Promise" in JavaScript? AnswerAn object for async task state 9. Which array method creates a new array by performing a function on every element? Answer\`map()\` 10. What does the "this" keyword refer to in a standard object method? AnswerThe object owning the method 11. How do you convert a JSON string into a JavaScript object? Answer\`JSON.parse()\` 12. What is "Hoisting" in JavaScript? AnswerMoving declarations to the top 13. Which operator is used to spread the elements of an array into another array? Answer\`...\` 14. What is an "anonymous function"? AnswerA function without a name 15. Which of these is a "falsy" value in JavaScript? Answer\`0\` 16. What is the purpose of the "async" keyword? AnswerTo return a Promise object 17. How do you check the length of an array "myArr"? Answer\`myArr.length\` 18. What does "DOM" stand for? AnswerDocument Object Model 19. Which keyword is used to stop a loop immediately? Answer\`break\` 20. What is the "event bubble"? AnswerEvent propagation upwards 21. Which symbol is used for template literals? Answer\`Backticks (\` \`)\` 22. What is the purpose of "use strict"? AnswerTo enforce cleaner code 23. What is "null" in JavaScript? AnswerIntentional empty value 24. Which method adds an item to the BEGINNING of an array? Answer\`unshift()\` 25. What does "NaN" stand for? AnswerNot a Number 26. Which function is used to execute a block of code after a specified delay? Answer\`setTimeout()\` 27. How do you check if an object has a specific property? Answer\`key in object\` 28. What is a "Closure"? AnswerPersistent scope access 29. Which keyword is used to inherit from another class? Answer\`extends\` 30. What is the default return value of a function that doesn't return anything? 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"Share on Pinterest")[Email]() ## Comments Was this useful? ## You might also enjoy More posts on similar topics [![TypeScript: Typed JavaScript Fundamentals](/_astro/hero.BXknL-oV_plxRs.webp)](/quizzes/post/typescript-fundamentals-quiz) ## [TypeScript: Typed JavaScript Fundamentals](/quizzes/post/typescript-fundamentals-quiz) - [Mohammad Abu Mattar](/authors/mohammad-abu-mattar) - [TypeScript](/quizzes/categories/typescript) - [Programming](/quizzes/categories/programming) - [Web Development](/quizzes/categories/web-development) - [Frontend](/quizzes/categories/frontend) Welcome to the TypeScript Basics Quiz! This quiz covers fundamental TypeScript concepts, static typing, and type-safe programming best practices. 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