Interact.jl allows you to use interactive widgets such as sliders, dropdowns and checkboxes to play with your Julia code:
To install Interact, run the following command in the Julia REPL:
Pkg.add("Interact")
The best way to learn to use the interactive widgets is to try out the example notebooks and the tutorial in the doc/notebooks/ directory. Start up IJulia from doc/notebooks/:
using IJulia
notebook()
To learn more, check out the documentation and the list of all available widgets.