libjavascriptcoregtk-4.0-18 2.26.3-0ubuntu0.18.04.1 (s390x binary) in ubuntu bionic

 JavaScriptCore is the JavaScript engine used in WebKit. It consists
 of the following building blocks: lexer, parser, start-up interpreter
 (LLInt), baseline JIT, a low-latency optimizing JIT (DFG), and a
 high-throughput optimizing JIT (FTL).
 .
 This build comes from the GTK+ port of WebKit (API version 4.0).
 .
 This package contains the shared libraries.