Introduction If you are a javascript developer, I believe you will use the developer tool of the browser to interact with the page that you're inspecting or test a piece of code. This console is a REPL (Read-eval-print-loop) or language Shell. A REPL is a simple, interactive programming environment that takes user input (Read), executes the user command (Evaluate), returns the result to the user (Print), and waits for the next user input (Loop). From java 9, we also have a REPL tool for java which called Java Shell Tool or in short JShell. Open Jshell: quoc ~ $ jshell | Welcome to JShell -- Version 15.0.2 | For an introduction type : / help intro jshell>