Editing JavaScript (section)

== Website client-side usage ==
JavaScript is the dominant [[client-side]] [[scripting language]] of the Web, with 99% of all [[website]]s using it for this purpose.<ref name="deployedstats" /> Scripts are embedded in or included from [[HTML]] documents and interact with the [[Document Object Model|DOM]].

All major [[web browser]]s have a built-in [[JavaScript engine]] that executes the [[Source code|code]] on the user's device.

=== Examples of scripted behavior ===
* Loading new [[web page]] content without reloading the page, via [[Ajax (programming)|Ajax]] or a [[WebSocket]]. For example, [[user (computing)|users]] of [[social media]] can send and receive messages without leaving the current page.
* Web page animations, such as fading objects in and out, resizing, and moving them.
* Playing [[browser game]]s.
* Controlling the [[Media player software|playback]] of [[streaming media]].
* Generating [[pop-up ad]]s or alert boxes.
* [[Data validation|Validating]] input values of a [[Form (HTML)|web form]] before the data is sent to a [[web server]].
* Logging data about the user's behavior then sending it to a server. The website owner can use this data for [[Web analytics|analytics]], [[ad tracking]], and [[personalization]].
*Redirecting a user to another page.
* Storing and retrieving data on the user's device, via the [[web storage|storage]] or [[Indexed Database API|IndexedDB]] standards.

=== Libraries and frameworks ===
Over 80% of websites use a third-party JavaScript [[Library (computing)|library]] or [[web framework]] as part of their client-side scripting.<ref name="lib_usage">{{cite web|url=https://w3techs.com/technologies/overview/javascript_library|title=Usage statistics of JavaScript libraries for websites|website=W3Techs|access-date=2021-04-09}}</ref>

[[jQuery]] is by far the most-used.<ref name="lib_usage" /> Other notable ones include <!--alphabetically is fair here-->[[Angular (web framework)|Angular]], [[Bootstrap (front-end framework)|Bootstrap]], [[Lodash]], [[Modernizr]], [[React (software)|React]], [[Underscore.js|Underscore]], and [[Vue.js|Vue]].<ref name="lib_usage" /> Multiple options can be used in conjunction, such as jQuery and Bootstrap.<ref>{{cite web |title=Using jQuery with Bootstrap |url=https://clouddevs.com/jquery/web-projects-with-bootstrap/ |website=clouddevs.com |date=10 June 2019 |access-date=17 March 2024}}</ref>

However, the term "Vanilla JS" was coined for websites not using any libraries or frameworks at all, instead relying entirely on standard JavaScript functionality.<ref>{{cite web |date=2020-06-16 |title=Vanilla JS |url=https://vanilla-js.com/ |url-status=live |archive-url=https://web.archive.org/web/20200616052335/https://vanilla-js.com/ |archive-date=June 16, 2020 |access-date=June 17, 2020 |website=vanilla-js.com}}</ref>