--- title: Type Narrowing in TypeScript | daily.dev description: A practical guide to TypeScript type narrowing covering multiple techniques: typeof type guards, truthiness narrowing, equality narrowing, discriminated... canonical: https://daily.dev/posts/type-narrowing-in-typescript-ljhybguro twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Type Narrowing in TypeScript | daily.dev og:description: A practical guide to TypeScript type narrowing covering multiple techniques: typeof type guards, truthiness narrowing, equality narrowing, discriminated... og:url: https://daily.dev/posts/type-narrowing-in-typescript-ljhybguro og:image: https://api.daily.dev/og/posts/LJHYbgURo.png og:image:alt: Type Narrowing in TypeScript 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. # Type Narrowing in TypeScript **[Playful Programming](https://daily.dev/sources/playfulprogramming)** · [@mainawycliffe](https://daily.dev/mainawycliffe) · 8 min read · 0 upvotes · 0 comments ## Summary A practical guide to TypeScript type narrowing covering multiple techniques: typeof type guards, truthiness narrowing, equality narrowing, discriminated unions, the 'in' operator, assignment narrowing, and instanceof checks. Each technique is explained with concrete code examples showing how TypeScript infers more precise types within conditional branches. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Visual Types](https://daily.dev/posts/visual-types-yqneyg40x) · Lobsters · 5 upvotes · 0 comments - [TypeScript Discriminated Unions: Safe Narrowing and Checks](https://daily.dev/posts/typescript-discriminated-unions-safe-narrowing-and-checks-bywqozkte) · SitePoint · 8 upvotes · 0 comments - [Beyond the basics: 21 TypeScript features you might not know about](https://daily.dev/posts/beyond-the-basics-21-typescript-features-you-might-not-know-about-oivxxtrie) · DEV · 27 upvotes · 0 comments --- Tags: [#javascript](https://daily.dev/tags/javascript), [#typescript](https://daily.dev/tags/typescript) [View this post on daily.dev](https://daily.dev/posts/type-narrowing-in-typescript-ljhybguro) ```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":"Type Narrowing in TypeScript","url":"https://daily.dev/posts/type-narrowing-in-typescript-ljhybguro","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/type-narrowing-in-typescript-ljhybguro"},"datePublished":"2026-03-16T21:47:38.387Z","dateModified":"2026-03-17T18:01:45.851Z","description":"A practical guide to TypeScript type narrowing covering multiple techniques: typeof type guards, truthiness narrowing, equality narrowing, discriminated...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/071ba8ae54bf6288b25d82522a26e6fb?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/071ba8ae54bf6288b25d82522a26e6fb?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Playful Programming","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Person","name":"Maina Wycliffe","url":"https://daily.dev/mainawycliffe","image":"https://lh3.googleusercontent.com/a-/AOh14GixkCfcFRGynHA6Q1do3acrQ2SJInlspCdn2KXZWw=s100","description":"Web Developer and Google Developer Expert","interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"EndorseAction"},"userInteractionCount":50}},"commentCount":0,"discussionUrl":"https://daily.dev/posts/type-narrowing-in-typescript-ljhybguro","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"javascript,typescript","timeRequired":"PT8M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Playful Programming","item":"https://daily.dev/sources/playfulprogramming"},{"@type":"ListItem","position":3,"name":"Type Narrowing in TypeScript"}]} ```