Interactive programming for Node.js. Speed up your JavaScript development!

hakk is a tool for Node.js that allows you to interactively develop, modify, and test your JavaScript code while it's running.

hakk watches your JavaScript source files, and hot updates any code you modify while your code is running. It also provides an interactive prompt (similar to the Node.js REPL) that lets you test individual parts of your program as you tinker with them.

hakk runs in your terminal and works alongside any code editor.

To install hakk, enter the following in your shell:

npm install -g hakk

To run hakk:

cd my-node-js-project
hakk index.js

If you edit any source file, hakk will hot-swap the modified variable, function or class. Existing code that hasn't been changed doesn't get reloaded: your program will maintain its running state. Things you can change include:

• Variables: All top-level variables can be modified or redefined on the fly, including variables that were already defined using const or let.
• Functions: You can define new functions, or change the implementation of an existing function.
• Classes: You can add new classes, and modify existing classes. If you add a new method or field to a class, existing instances of that class will immediately adopt the new behavior.
• Imports: You can use require or import to import new library APIs in your running program.

hakk is built around the familiar Node.js REPL interface. You can call functions you are working on in your source file to test them as you develop them. You can enter a top-level variable and the REPL will return that variable's value. You can modify variables in the REPL, including those that were declared with const!

hakk is an experimental tool. Bug reports and other feedback is welcome at https://github.com/arthuredelstein/hakk

(c) 2023 Arthur Edelstein