199 lines
12 KiB
Markdown
199 lines
12 KiB
Markdown
---
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title: "Primitive - Glossary | MDN"
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chunk: 1/3
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source: "https://developer.mozilla.org/en-US/docs/Glossary/Primitive"
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category: "reference"
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tags: "web, html, css, javascript, documentation"
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date_saved: "2026-05-05T05:40:46.758789+00:00"
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instance: "kb-cron"
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---
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* [Skip to main content](https://developer.mozilla.org/en-US/docs/Glossary/Primitive#content)
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* [Skip to search](https://developer.mozilla.org/en-US/docs/Glossary/Primitive#search)
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[ MDN ](https://developer.mozilla.org/en-US/)
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HTML
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[HTML: Markup language](https://developer.mozilla.org/en-US/docs/Web/HTML)
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HTML reference
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* [Elements](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements)
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* [Global attributes](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Global_attributes)
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* [Attributes](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Attributes)
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* [See all…](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference "See all HTML references")
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HTML guides
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* [Responsive images](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides/Responsive_images)
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* [HTML cheatsheet](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides/Cheatsheet)
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* [Date & time formats](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides/Date_and_time_formats)
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* [See all…](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides "See all HTML guides")
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Markup languages
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* [SVG](https://developer.mozilla.org/en-US/docs/Web/SVG)
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* [MathML](https://developer.mozilla.org/en-US/docs/Web/MathML)
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* [XML](https://developer.mozilla.org/en-US/docs/Web/XML)
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CSS
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[CSS: Styling language](https://developer.mozilla.org/en-US/docs/Web/CSS)
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CSS reference
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* [Properties](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties)
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* [Selectors](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Selectors)
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* [At-rules](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/At-rules)
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* [Values](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Values)
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* [See all…](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference "See all CSS references")
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CSS guides
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* [Box model](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Box_model/Introduction)
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* [Animations](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Animations/Using)
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* [Flexbox](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Flexible_box_layout/Basic_concepts)
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* [Colors](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Colors/Applying_color)
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* [See all…](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides "See all CSS guides")
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Layout cookbook
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* [Column layouts](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook/Column_layouts)
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* [Centering an element](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook/Center_an_element)
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* [Card component](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook/Card)
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* [See all…](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook)
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JavaScriptJS
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[JavaScript: Scripting language](https://developer.mozilla.org/en-US/docs/Web/JavaScript)
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JS reference
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* [Standard built-in objects](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects)
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* [Expressions & operators](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators)
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* [Statements & declarations](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements)
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* [Functions](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions)
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* [See all…](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference "See all JavaScript references")
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JS guides
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* [Control flow & error handing](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Control_flow_and_error_handling)
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* [Loops and iteration](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Loops_and_iteration)
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* [Working with objects](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_objects)
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* [Using classes](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_classes)
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* [See all…](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide "See all JavaScript guides")
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Web APIs
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[Web APIs: Programming interfaces](https://developer.mozilla.org/en-US/docs/Web/API)
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Web API reference
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* [File system API](https://developer.mozilla.org/en-US/docs/Web/API/File_System_API)
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* [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API)
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* [Geolocation API](https://developer.mozilla.org/en-US/docs/Web/API/Geolocation_API)
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* [HTML DOM API](https://developer.mozilla.org/en-US/docs/Web/API/HTML_DOM_API)
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* [Push API](https://developer.mozilla.org/en-US/docs/Web/API/Push_API)
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* [Service worker API](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API)
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* [See all…](https://developer.mozilla.org/en-US/docs/Web/API "See all Web API guides")
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Web API guides
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* [Using the Web animation API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Animations_API/Using_the_Web_Animations_API)
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* [Using the Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch)
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* [Working with the History API](https://developer.mozilla.org/en-US/docs/Web/API/History_API/Working_with_the_History_API)
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* [Using the Web speech API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Speech_API/Using_the_Web_Speech_API)
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* [Using web workers](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Using_web_workers)
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All
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[All web technology](https://developer.mozilla.org/en-US/docs/Web)
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Technologies
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* [Accessibility](https://developer.mozilla.org/en-US/docs/Web/Accessibility)
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* [HTTP](https://developer.mozilla.org/en-US/docs/Web/HTTP)
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* [URI](https://developer.mozilla.org/en-US/docs/Web/URI)
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* [Web extensions](https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions)
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* [WebAssembly](https://developer.mozilla.org/en-US/docs/WebAssembly)
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* [WebDriver](https://developer.mozilla.org/en-US/docs/Web/WebDriver)
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* [See all…](https://developer.mozilla.org/en-US/docs/Web "See all web technology references")
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Topics
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* [Media](https://developer.mozilla.org/en-US/docs/Web/Media)
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* [Performance](https://developer.mozilla.org/en-US/docs/Web/Performance)
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* [Privacy](https://developer.mozilla.org/en-US/docs/Web/Privacy)
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* [Security](https://developer.mozilla.org/en-US/docs/Web/Security)
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* [Progressive web apps](https://developer.mozilla.org/en-US/docs/Web/Progressive_web_apps)
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Learn
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[Learn web development](https://developer.mozilla.org/en-US/docs/Learn_web_development)
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Frontend developer course
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* [Getting started modules](https://developer.mozilla.org/en-US/docs/Learn_web_development/Getting_started)
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* [Core modules](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core)
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* [MDN Curriculum](https://developer.mozilla.org/en-US/curriculum/)
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* [Check out the video course from Scrimba, our partner](https://scrimba.com/frontend-path-c0j?via=mdn-learn-navbar)
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Learn HTML
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* [Structuring content with HTML module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Structuring_content)
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Learn CSS
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* [CSS styling basics module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Styling_basics)
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* [CSS layout module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/CSS_layout)
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Learn JavaScript
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* [Dynamic scripting with JavaScript module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Scripting)
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Tools
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Discover our tools
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* [Playground](https://developer.mozilla.org/en-US/play)
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* [HTTP Observatory](https://developer.mozilla.org/en-US/observatory)
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* [Border-image generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Backgrounds_and_borders/Border-image_generator)
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* [Border-radius generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Backgrounds_and_borders/Border-radius_generator)
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* [Box-shadow generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Backgrounds_and_borders/Box-shadow_generator)
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* [Color format converter](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Colors/Color_format_converter)
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* [Color mixer](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Colors/Color_mixer)
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* [Shape generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Shapes/Shape_generator)
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About
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Get to know MDN better
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* [About MDN](https://developer.mozilla.org/en-US/about)
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* [Advertise with us](https://developer.mozilla.org/en-US/advertising)
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* [Community](https://developer.mozilla.org/en-US/community)
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* [MDN on GitHub](https://github.com/mdn)
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[Blog](https://developer.mozilla.org/en-US/blog/)
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1. [Glossary](https://developer.mozilla.org/en-US/docs/Glossary)
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2. [Primitive](https://developer.mozilla.org/en-US/docs/Glossary/Primitive)
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# Primitive
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In [JavaScript](https://developer.mozilla.org/en-US/docs/Glossary/JavaScript), a **primitive** (primitive value, primitive data type) is data that is not an [object](https://developer.mozilla.org/en-US/docs/Glossary/Object) and has no [methods](https://developer.mozilla.org/en-US/docs/Glossary/Method) or [properties](https://developer.mozilla.org/en-US/docs/Glossary/Property/JavaScript). There are 7 primitive data types:
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* [string](https://developer.mozilla.org/en-US/docs/Glossary/String)
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* [number](https://developer.mozilla.org/en-US/docs/Glossary/Number)
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* [bigint](https://developer.mozilla.org/en-US/docs/Glossary/BigInt)
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* [boolean](https://developer.mozilla.org/en-US/docs/Glossary/Boolean)
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* [undefined](https://developer.mozilla.org/en-US/docs/Glossary/Undefined)
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* [symbol](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol)
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* [null](https://developer.mozilla.org/en-US/docs/Glossary/Null)
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Most of the time, a primitive value is represented directly at the lowest level of the language implementation.
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All primitives are _immutable_ ; that is, they cannot be altered. It is important not to confuse a primitive itself with a variable assigned a primitive value. The variable may be reassigned to a new value, but the existing value can not be changed in the ways that objects, arrays, and functions can be altered. The language does not offer utilities to mutate primitive values.
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Primitives have no methods but still behave as if they do. When properties are accessed on primitives, JavaScript _auto-boxes_ the value into a wrapper object and accesses the property on that object instead. For example, `"foo".includes("f")` implicitly creates a [`String`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String) wrapper object and calls `String.prototype.includes()` on that object. This auto-boxing behavior is not observable in JavaScript code but is a good mental model of various behaviors — for example, why "mutating" primitives does not work (because `str.foo = 1` is not assigning to the property `foo` of `str` itself, but to an ephemeral wrapper object).
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## In this article
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* [See also](https://developer.mozilla.org/en-US/docs/Glossary/Primitive#see_also)
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## [See also](https://developer.mozilla.org/en-US/docs/Glossary/Primitive#see_also)
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* [JavaScript data types](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Data_structures)
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* [Primitive data type](https://en.wikipedia.org/wiki/Primitive_data_type) (Wikipedia)
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* Related glossary terms:
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* [JavaScript](https://developer.mozilla.org/en-US/docs/Glossary/JavaScript)
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* [string](https://developer.mozilla.org/en-US/docs/Glossary/String)
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* [number](https://developer.mozilla.org/en-US/docs/Glossary/Number)
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* [bigint](https://developer.mozilla.org/en-US/docs/Glossary/BigInt)
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* [boolean](https://developer.mozilla.org/en-US/docs/Glossary/Boolean)
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* [null](https://developer.mozilla.org/en-US/docs/Glossary/Null)
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* [undefined](https://developer.mozilla.org/en-US/docs/Glossary/Undefined)
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* [symbol](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol) |