XBL

XBL (XML Binding Language) is an <a href="/facts/XML/clNgUfWk">XML</a>-based <a href="/facts/Markup_language/WwhlNVIu">markup language</a> for altering the behavior of <a href="/facts/XUL/VoNXYx92">XUL</a> <a href="/facts/Graphical_widget/SuVeScB2">widgets</a>. It was devised at <a href="/facts/Netscape/JGWlEUI7">Netscape</a> in the late 1990s as an extension of XUL.
The primary use of XBL was in the <a href="/facts/Firefox/xez2zv8H">Firefox</a> <a href="/facts/Web_browser/2pfyymLs">web browser</a>, but <a href="/facts/Mozilla_Corporation/AGF9famv">Mozilla</a> deprecated it in 2017 and completely removed it from Firefox in 2019. However, the <a href="/facts/Pale_Moon_(web_browser)/8Wye08yN">UXP</a> <a href="/facts/Fork_(software_development)/D6khxhpr">fork</a> of Firefox intends to continue supporting XBL indefinitely.
Mozilla attempted to standardize XBL 2.0 via <a href="/facts/W3C/lGWmhF6M">W3C</a> in 2007, but due to lack of interest from other web browser vendors, abandoned it in 2012.
The <a href="/facts/Web_Components/zQzBNnef">Shadow DOM</a> specification acknowledges XBL as a strong influence.

XBL open-in-new

XBL