This script uses a regular Stochastic RSI formula and then runs Ehlers' Super Smoother on top of it. It also provides buy/sell signals on crossovers.
The script is inspired by LazyBear Ehlers-Smoothed Stochastic RSI with Roofing Filter, except I find that the Roofing filter (existing implementation) does not work well near extreme price changes, where a regular formula is preferable. The Ehlers Super Smoother however is excellent and seems to provide earlier signals in most cases than an EMA-EMA smoother. Combined, the super-smoother and regular Stochastic RSI formula provide very good results.