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A '''single-page application''' ('''SPA''') is a [[web application]] with a single [[web page]].  

== Description ==

In SPA, the user navigates through content much like navigating from one web page to another, but in fact the browser remains on a single page.

In an SPA, all of the necessary code -- [[HTML]], [[JavaScript]], and [[Cascading Style Sheets|CSS]] -- is either retrieved with a single page load, or added dynamically (via JavaScript).  

The page loads once, the web application is ready to use, with additional code added dynamically as needed.

The page does not reload at any point in the process, nor does control transfer to another page.

== URL in address bar ==

The [[URL]] in the [[browser address bar]] may change.  This is done with [[JavaScript]].

== Process ==

Interaction with the single page application typically involves dynamic communication with a [[web server]].  

* The application makes a request to the server (typically because of a user action, or a timer)
* The server responds with some data
* The web application uses this data to update the browser

== User perception of separate pages ==

Modern web technologies -- such as those included in the [[HTML5]] [https://en.wikipedia.org/wiki/Comparison_of_layout_engines_(HTML5)#APIs pushState()] [[Application programming interface|API]] -- can help provide the perception and navigability of separate logical pages in the application.

== Functions ==

Key functions of single-page applications:

* Communication with the server
* Data binding
* Templating system
* Layout and partials
* Routing

== See also ==

* [[AngularJS]]
* [[Application programming interface]]
* [[Backbone.js]]
* [[Dynamic web page]]
* [[Dynamic web site]]
* [[Web application]]

== External links ==

* [https://en.wikipedia.org/wiki/Single-page_application Single-page application] @ Wikipedia
* [http://singlepageappbook.com/ Single page apps in depth]

[[Category:Web design and development]]