--- title: Async vs Defer in JavaScript: Which is Better?🤔 | daily.dev description: Learn about the async and defer attributes used when including external JavaScript files in HTML documents. Understand their differences, how they affect... canonical: https://daily.dev/posts/async-vs-defer-in-javascript-which-is-better--rjwmqpqo5 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Async vs Defer in JavaScript: Which is Better?🤔 | daily.dev og:description: Learn about the async and defer attributes used when including external JavaScript files in HTML documents. Understand their differences, how they affect... og:url: https://daily.dev/posts/async-vs-defer-in-javascript-which-is-better--rjwmqpqo5 og:image: https://api.daily.dev/og/posts/rJWMQPqO5.png og:image:alt: Async vs Defer in JavaScript: Which is Better?🤔 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. # Async vs Defer in JavaScript: Which is Better?🤔 **[DEV](https://daily.dev/sources/devto)** · [@fidalmathew](https://daily.dev/fidalmathew) · 2 min read · 634 upvotes · 34 comments ## Summary Learn about the async and defer attributes used when including external JavaScript files in HTML documents. Understand their differences, how they affect script execution, and when to use them. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Community discussion Top comments from developers on daily.dev. **@matyleo** · 8 upvotes > Helpful explanation that gets straight to the point! Nice little art. **@minhnh** · 4 upvotes > concise, easy to digest. we should have more articles like this! **@ivanlynch** · 2 upvotes > Nice post! **@sudouken** · 2 upvotes > This article is a great overview. For a deeper dive, particularly into the `DOMContentLoaded` event check out this article: > > https://javascript.info/script-async-defer **@muhammadidrees** · 1 upvotes > impresive ## 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), [#performance](https://daily.dev/tags/performance), [#html](https://daily.dev/tags/html) [View this post on daily.dev](https://daily.dev/posts/async-vs-defer-in-javascript-which-is-better--rjwmqpqo5) ```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":"TechArticle","headline":"Async vs Defer in JavaScript: Which is Better?🤔","url":"https://daily.dev/posts/async-vs-defer-in-javascript-which-is-better--rjwmqpqo5","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/async-vs-defer-in-javascript-which-is-better--rjwmqpqo5"},"datePublished":"2024-03-01T18:35:46.689Z","dateModified":"2024-05-09T08:43:33.910Z","description":"Learn about the async and defer attributes used when including external JavaScript files in HTML documents. 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Nice little art.","datePublished":"2024-03-02T13:45:26.447Z","url":"https://daily.dev/posts/rJWMQPqO5#c-rzWnojgOB","author":{"@type":"Person","name":"Matyáš Leon Dušek","url":"https://daily.dev/matyleo","image":"https://lh3.googleusercontent.com/a/ACg8ocIcBWmZEyEi-uGxy1pOog9ZUFQoRua_rGNMDR2lAzHevzI=s96-c"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":8}},{"@type":"Comment","text":"concise, easy to digest. we should have more articles like this!","datePublished":"2024-03-04T02:18:10.363Z","url":"https://daily.dev/posts/rJWMQPqO5#c-Pg6qkSOJ2","author":{"@type":"Person","name":"Minh Nguyen","url":"https://daily.dev/minhnh","image":"https://avatars.githubusercontent.com/u/6817741?v=4"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":4}},{"@type":"Comment","text":"Nice post!","datePublished":"2024-03-02T18:10:38.982Z","url":"https://daily.dev/posts/rJWMQPqO5#c-xkyWkU9oT","author":{"@type":"Person","name":"ivanlynch","url":"https://daily.dev/ivanlynch","image":"https://media.daily.dev/image/upload/s--XvTPvuHQ--/f_auto/v1707839958/avatars/avatar_G8nDHTKFt9FXLQAWHIZEA"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":2}},{"@type":"Comment","text":"This article is a great overview. For a deeper dive, particularly into the DOMContentLoaded event check out this article:\nhttps://javascript.info/script-async-defer","datePublished":"2024-03-04T05:36:42.197Z","url":"https://daily.dev/posts/rJWMQPqO5#c-SAGtYA9o3","author":{"@type":"Person","name":"Matthew","url":"https://daily.dev/sudouken","image":"https://media.daily.dev/image/upload/s--jRwVjerf--/f_auto/v1755725028/avatars/avatar_l1V0jO5VncYwbcQDE0JQ1?_a=BAMClqZW0"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":2}},{"@type":"Comment","text":"impresive","datePublished":"2024-03-04T02:32:37.716Z","url":"https://daily.dev/posts/rJWMQPqO5#c-y5Ijdnsq3","author":{"@type":"Person","name":"Muhammad Idrees","url":"https://daily.dev/muhammadidrees","image":"https://lh3.googleusercontent.com/a/ACg8ocIWVN8uV0JvuYtf42i8DDuAfQhRXk3J6XY_pRMY_U91=s96-c"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1}}]} ```