Single-page application

A single-page application (SPA) is a web application or web site that fits on a single web page with the goal of providing a user experience similar to that of a desktop application. In an SPA, either all necessary code – HTML, JavaScript, and CSS – is retrieved with a single page load, or the appropriate resources are dynamically loaded and added to the page as necessary, usually in response to user actions. The page does not reload at any point in the process, nor does control transfer to another page, although the location hash or the HTML5 History API can be used to provide the perception and navigability of separate logical pages in the application. Interaction with the single page application often involves dynamic communication with the web server behind the scenes.

The origins of the term single-page application are unclear, though the concept was discussed at least as early as 2003.Stuart (stunix) Morris wrote the Self-Contained website at slashdotslash.com with the same goals and functions in April 2002 and later the same year, Lucas Birdeau, Kevin Hakman, Michael Peachey and Evan Yeh described a single page application implementation in the US patent 8,136,109.

JavaScript can be used in a web browser to display the user interface (UI), run application logic, and communicate with a web server. Mature open-source libraries are available that support the building of an SPA, reducing the amount of JavaScript code the developer has to write.

There are various techniques available that enable the browser to retain a single page even when the application requires server communication.

Web browser JavaScript frameworks, such as AngularJS, Ember.js, Meteor.js, ExtJS and React have adopted SPA principles.

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