boxplus: a lightweight pop-up window engine


boxplus is an ultimate lightweight pop-up window implementation (commonly known as lightbox) that can show images, video and other multimedia content including custom HTML content. boxplus exhibits a high degree of personalization with features like thumbnail bar of images inside the lightbox for fast navigation between items, image captions supporting HTML, auto-fit content and auto-center as well as several themes mimicking various popular lightbox implementations. boxplus for Joomla adds a thin layer around boxplus client-side JavaScript code to expose its functionality in the Joomla framework. The boxplus engine is written entirely in plain JavaScript, it incurs no extra overhead and you should not expect script conflicts, which may arise with other plug-ins built on top of different JavaScript libraries.

This page discusses boxplus, a stand-alone lightbox script as well as a self-contained Joomla plug-in. Some of the particulars may differ from those of boxplus for jQuery, which is shipped with sigplus version 1.4.x.


  • Supports all modern browsers, including Chrome, Safari, Firefox, Edge, Internet Explorer (≥ 11) and Opera.
  • Displays a wide range of content types. Supports images, video, inline and external HTML (iframe), PDF documents, etc.
  • Supports captions. Each image or content item can be assigned a title and a caption, which can make use of HTML tags.
  • Pop-up window centers vertically and horizontally. Vertical centering takes into account any caption text. The pop-up window remains centered when the user scrolls down or across the page, or resizes the browser window.
  • Various navigation controls. You can navigate to the next or previous image with the mouse or the keyboard (left arrow and right arrow), or use the thumbnail bar at the bottom to jump to any specific item, press HOME to jump to the first and END to the last content item.
  • Fit to browser window. Large images are automatically reduced to fit available browser window space. The pop-up window can be expanded with the enlarge control in the upper right corner to view the image in its original size.
  • Configurable layout. Panel containing captions and navigation icons can be aligned to above, at the top, at the bottom, or below the content being displayed.
  • Asynchronous operation with no dead time delay. The script launches as soon as the document structure is available, even if some images are still being downloaded. Only those content items are retrieved that are shown to the visitor.
  • Easily customizable appearance using valid CSS. All styling is done using cascading style sheet rules, which allows for simple theming.
  • Small network footprint. Even while boxplus has many extra features, its compressed size is comparable to Slimbox 2, which claims to be the smallest lightbox script available for the MooTools framework (with a footprint of 4 KB).
  • 100% CSS and JavaScript. The implementation needs no additional dependencies to work.

See the boxplus demo page for an on-line demonstration of some of the features boxplus has to offer.

Solving common problems

Usually, boxplus is not used in isolation but as part of a site. Page template CSS style sheet files are a common cause of layout problems with boxplus. Some agressive templates may apply unusual properties to certain elements globally. As HTML elements boxplus uses are inserted below the body element in the HTML DOM tree, boxplus is affected by rules with global scope. For example, if a template sets z-index:1 with a global element selector img, it will make all absolutely positioned images cover other absolutely positioned elements, hiding boxplus overlay navigation controls, the enlarge/shrink control as well as thumbnail images inside the pop-up window. To remedy the issue, any such global declarations should be reset before boxplus styles would be applied using a Reset stylesheet or CSS reset. Such a stylesheet will clear most unusual style applications.


The following table compares boxplus to other lightweight pop-up window engines.

Comparison of boxplus to other engines
  boxplus Slimbox Slimbox2 prettyPhoto FancyBox
Version 1.0 1.58 2.04 3.0 1.3.4
JavaScript library dependency (none) MooTools jQuery jQuery jQuery
Minified script size [bytes] 12714 4681 4123 21240 15624
Multiple themes yes no no yes yes
Displays images yes yes yes yes yes
Fit-to-window for large images yes no no yes yes
Thumbs in pop-up window for fast navigation yes no no yes no
Wide-screen arrangement [*] yes no no no no
Panel for image background information yes no no no no
HTML in image captions yes yes yes yes yes
Displays custom HTML content yes no no yes yes
Displays Flash content and video yes no no yes yes
Displays HTML5 video yes no no no no
Displays Picasa web albums yes no no no no
Multiple languages yes no no no no
Multiple configurations on a single page yes no no yes yes
Multiple themes on a single page yes no no no no
Caption and metadata script callbacks yes no no no no
Browser compatibility Internet Explorer 7 and laterFirefoxChromeSafariOpera Internet Explorer 6 and laterFirefoxChromeSafariOpera Internet Explorer 6 and laterFirefoxChromeSafariOpera Internet Explorer 6 and laterFirefoxChromeSafari Internet Explorer 6 and laterFirefoxChromeSafariOpera

If you find that data in the table is inaccurate, please e-mail the developer and the table will be updated.

License and status

boxplus is licensed under the GPL. It is a non-commercial project with a goal to provide a lightweight, yet versatile tool to display images, video and other multimedia content on a web page. As such, it depends on donations for further development. Especially if you use boxplus in a commercial environment, you are strongly encouraged to make a donation.

Donations in EUR
Donations in USD


The latest public release of boxplus is available for download from BitBucket. The files in the subfolders css and js have no external dependencies; they can be used stand-alone.

{rokstyle} .article-content table img { margin:1px; } {/rokstyle}