jscript was JavaScript engine: https://en.wikipedia.org/wiki/JScript

J++ was a 'clone' of Java https://en.wikipedia.org/wiki/Visual_J%2B%2B . Sun sued Microsoft, https://www.cnet.com/tech/tech-industry/sun-microsoft-settle...

and that's how .Net was born ( with https://en.wikipedia.org/wiki/Visual_J_Sharp to ensure transition)