No relation except the first four letters of the name.
Javascript (see the first link below) is a scripting language (see second link below) loosely based on the shared C syntax of both Java and C++. Scripting languages associated with HTML (like Sun’s Javascript, Microsoft’s proprietary version called JScript, both based on Java, and Microsoft’s VBScript based on the Visual Basic programming language) are interpreted and executed at run-time and interact with the web page’s Document Object Model (DOM) to access the HTML Elements. Javascript usually only runs client side in a browser as part of the HTML code loaded as a web page.
Java (see the third link below) is a sophisticated platform-independent Object-Oriented Programming (OOP) language (see the fourth link below), based on C/C++, with automated garbage disposal that eliminates most memory leaks. Java can be written as a standalone GUI application or packaged as a web Graphical User Interface (GUI) in an Applet (so like Javascript, it can also run in a browser). The more common use of Java is in servlets and JSPs running on an Enterprise Application Server in a DMZ behind a web server & firewall that produces Enterprise web functionality (for example, as financial apps like online shopping carts, or online financial investment apps, etc.).