EZ Statistics is a web tool for running statistical tests written in JavaScript. It supports a range of the most commonly used parametric and non-parametric tests.
You can try it out here.
EZ Statistics runs entirely in the browser and doesn't need a web server. Just open the html files in a browser to run it locally.
All modifications to the code shall be done in the JavaScript files in the js folder. When the code modifications are finished, the jscombiner.py Python script must be run to combine all js files into one.
The library version can be changed in the Python script. Note that if you change version, you must also change the filename of the JavaScript library in the html files.