--- title: JavaScript is easy... Until you meet these confusing... description: JavaScript may seem easy until you encounter concepts like undefined vs. null, hoisting, the 'this' keyword, callbacks and promises, scope and closure,... canonical: https://daily.dev/posts/javascript-is-easy-until-you-meet-these-confusing-concepts--m9uvx2lj9 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: JavaScript is easy... Until you meet these confusing concepts. | daily.dev og:description: JavaScript may seem easy until you encounter concepts like undefined vs. null, hoisting, the 'this' keyword, callbacks and promises, scope and closure,... og:url: https://daily.dev/posts/javascript-is-easy-until-you-meet-these-confusing-concepts--m9uvx2lj9 og:image: https://api.daily.dev/og/posts/M9Uvx2lj9.png og:image:alt: JavaScript is easy... Until you meet these confusing concepts. og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # JavaScript is easy... Until you meet these confusing concepts. **[Web & App Development ](https://daily.dev/sources/codefort)** · [@ayushdev108](https://daily.dev/ayushdev108) · 2 min read · 633 upvotes · 44 comments ## Summary JavaScript may seem easy until you encounter concepts like undefined vs. null, hoisting, the 'this' keyword, callbacks and promises, scope and closure, prototypal inheritance, and the event loop. Understanding these concepts is crucial to mastering JavaScript. ## Content JavaScript is easy... Until you meet these confusing concepts. Let's break them down for clarity. → Undefined vs. Null. Undefined means a variable has been declared but not assigned a value. Null means a variable is intentionally empty. Know the difference to avoid errors. → Hoisting. JavaScript moves variable and function declarations to the top of their scope. This can lead to unexpected results. Understand hoisting to write better code. → This keyword. The "this" keyword can change based on how a function is called. It can refer to the global object, the object calling the method, or be undefined in strict mode. Grasp its context to avoid confusion. → Callbacks and Promises. Callbacks are functions passed as arguments. They can lead to callback hell. Promises help manage asynchronous operations better. Use them for cleaner code. → Scope and Closure. Scope determines variable access. Closure allows a function to remember its outer scope. They are key to understanding JavaScript's behavior. → Prototypal Inheritance. JavaScript uses prototypes for inheritance. Objects can inherit properties from other objects. Learn this to utilize JavaScript's full power. → Event Loop. JavaScript is single-threaded. The event loop handles asynchronous tasks. Understanding it helps manage performance and responsiveness. JavaScript can seem complex. But with a clear grasp of these concepts, you can master it. Dive in and explore. ## Community discussion Top comments from developers on daily.dev. **@k4ruy** · 11 upvotes > I'm a student and for me is not easy to learn JavaScript. maybe someone can help me with some tips and tricks? **@rakib8680** · 1 upvotes > great **@hazielmagallanes** · 1 upvotes > Where is the complexity on this? I mean, this is just programming, those aren't just JavaScript concepts, maybe undefined vs null but that's very simple. **@nhatty** · 1 upvotes > Thanks for reminding **@whoami89** · 1 upvotes > A small detail for callbacks vs. promises, not all functions accepting callbacks are asynchronous. So, you can still end up in callback hell without a thoughtful plan. ## Similar posts on daily.dev - [Don’t just attend KubeCon \+ CloudNativeCon, Merge Forward your experience\!](https://daily.dev/posts/don-t-just-attend-kubecon-cloudnativecon-merge-forward-your-experience--l0rpp73x8) · CNCF · 1 upvotes · 0 comments - [Announcing H2 2026 KCDs](https://daily.dev/posts/announcing-h2-2026-kcds-m96goajm1) · CNCF · 1 upvotes · 0 comments - [Two months of Open Community Groups](https://daily.dev/posts/two-months-of-open-community-groups-asf52zhbs) · CNCF · 0 upvotes · 0 comments - [CNCF Unveils Schedule for KubeCon \+ CloudNativeCon Europe 2026](https://daily.dev/posts/cncf-unveils-schedule-for-kubecon-cloudnativecon-europe-2026-ikhcoa5cb) · CNCF · 2 upvotes · 0 comments - [CNCF Debuts KubeCon \+ CloudNativeCon Japan 2026 Schedule](https://daily.dev/posts/cncf-debuts-kubecon-cloudnativecon-japan-2026-schedule-xp5pyudub) · CNCF · 1 upvotes · 0 comments --- Tags: [#webdev](https://daily.dev/tags/webdev), [#javascript](https://daily.dev/tags/javascript) [View this post on daily.dev](https://daily.dev/posts/javascript-is-easy-until-you-meet-these-confusing-concepts--m9uvx2lj9) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"DiscussionForumPosting","mainEntityOfPage":"https://daily.dev/posts/javascript-is-easy-until-you-meet-these-confusing-concepts--m9uvx2lj9","headline":"JavaScript is easy... Until you meet these confusing concepts.","text":"JavaScript may seem easy until you encounter concepts like undefined vs. null, hoisting, the 'this' keyword, callbacks and promises, scope and closure, prototypal inheritance, and the event loop. Understanding these concepts is crucial to mastering JavaScript.","url":"https://daily.dev/posts/javascript-is-easy-until-you-meet-these-confusing-concepts--m9uvx2lj9","datePublished":"2025-03-21T03:43:06.223Z","dateModified":"2025-03-21T03:43:18.129Z","author":{"@type":"Person","name":"Ayush Saurav","url":"https://daily.dev/ayushdev108","image":"https://lh3.googleusercontent.com/a/ACg8ocK5Mdy-nzmbYVdyp1UJf8NiFrdSzS6W-RR3RLRTXzG6Pm1rTv7w=s96-c","interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"EndorseAction"},"userInteractionCount":285}},"image":"https://media.daily.dev/image/upload/s--6dWFaGpw--/f_auto/v1742528586/posts/M9Uvx2lj9","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":633},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":44}],"comment":[{"@type":"Comment","text":"I’m a student and for me is not easy to learn JavaScript. maybe someone can help me with some tips and tricks?","datePublished":"2025-04-06T14:03:06.079Z","url":"https://daily.dev/posts/M9Uvx2lj9#c-8GnPfb1Hf","author":{"@type":"Person","name":"Yuriy T","url":"https://daily.dev/k4ruy","image":"https://avatars.githubusercontent.com/u/160423212?v=4"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":11}},{"@type":"Comment","text":"great","datePublished":"2025-04-08T12:18:12.075Z","url":"https://daily.dev/posts/M9Uvx2lj9#c-H3jjn0RZA","author":{"@type":"Person","name":"Abdullah Al Rakib","url":"https://daily.dev/rakib8680","image":"https://avatars.githubusercontent.com/u/121743420?v=4"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1}},{"@type":"Comment","text":"Where is the complexity on this? I mean, this is just programming, those aren’t just JavaScript concepts, maybe undefined vs null but that’s very simple.","datePublished":"2025-07-05T03:21:03.042Z","url":"https://daily.dev/posts/M9Uvx2lj9#c-rFcYsL0FR","author":{"@type":"Person","name":"Haziel Magallanes","url":"https://daily.dev/hazielmagallanes","image":"https://avatars.githubusercontent.com/u/111313705?v=4"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1}},{"@type":"Comment","text":"Thanks for reminding","datePublished":"2025-04-07T06:23:11.091Z","url":"https://daily.dev/posts/M9Uvx2lj9#c-FooXLZdDW","author":{"@type":"Person","name":"Natnael Kibrom","url":"https://daily.dev/nhatty","image":"https://media.daily.dev/image/upload/s--zlWrDhPr--/f_auto/v1753423417/avatars/avatar_c1bIbA8vKPyAV8Vp6tQRz?_a=BAMAK+ZW0"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1}},{"@type":"Comment","text":"A small detail for callbacks vs. promises, not all functions accepting callbacks are asynchronous. 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