[[File:Jsmess in Chromium.png|thumb|upright=1.3|JSMESS emulating a CPC6128 in Chromium 30 on Linux (with copious debug messages)]]
[[File:Jsmess firefox zoomed.png|thumb|upright=1.3|JSMESS in Firefox 24 (same rendering resolution but using page zoom to enlarge the CPC screen)]]
'''JSMESS''' ("JavaScript MESS") is a was an ongoing JavaScript translation port of MESS (now simply called [[MESSMAME]] that runs in as of 0.162) for modern web browsers like Chrome and Firefox. Despite being in its beta stage right now, JSMESS is already used by the Internet Archive to make their Historical Software Collection playable in web browsers.
CPC emulation speed is about 100% in Firefox and a little slower Since MAME 0.168 (released in November 2015), JSMESS is no longer necessary as evident from the slower CPC startup messagesMAME can compile to JavaScript (using Emscripten's emmake command) in Chrome when running out of the browsers on an entry-level 2012 PCbox. The chief remaining issues of JSMESS are spotty sound support and some bad keymapping[http://mamedev.org/releases/whatsnew_0168.txt]
==History and development roadmap==
As of October 2013, sound only works in Firefox and not in Chrome/Chromium. Emulation speed in Firefox is better than in Chrome, presumably because Firefox has better support for Emscripten's asm.js-based JS code. Internet Explorer 10 was supposedly supported very well by earlier versions of JSMESS with up to [https://github.com/jsmess/jsmess/wiki/Status 100% emulation performance] (including working sound) but the current JSMESS exits with an Emscripten error in IE 10.
The joystick is mapped to Alt and the arrow keys by default. The development version of JSMESS at archive.org also has support for USB gamepads but no sound.
==Usage on web pages and CPC6128 demo page==
==Links==
;General info
*[httphttps://jsmess.textfilesgithub.com/ jsmess/jsmess Official site]
*[http://archive.org/details/internetarchivecelebration20131024?start=2544 Video of Jason Scott presenting JSMESS and the Historical Software Collection] at the Internet Archive
*[http://archiveteam.org/index.php?title=Javascript_Mess Archive Team wiki page] about JSMESS
;Demos
*[http://mdoege.github.io/jsmess/ CPC6128/Sub Hunter demo page]
*[httphttps://archive.org/details/historicalsoftware Historical Software Collectionconsolelivingroom The Console Living Room] at the Internet Archive
[[Category:Emulator]]