The values of the Stochastic Levels on Chart indicator are calculated using Reverse Engineering calculations starting from default Stochastic formula : 100 * (close - lowest(low, length)) / (highest(high, length) - lowest(low, length)).
I added options for users to define the Extreme Overbought and Oversold values, also simple Oversold and Overbought values of the stochastic, default Extreme Overbought at 100, Extreme Oversold at 0, the 20 for Oversold and 80 as Overbought, plus the middle stochastic level = 50.
The script has included a color coded 20 SMA that will turn red when the 20 SMA is falling and green when it is rising, also there are bollinger bands using 2 standard deviation plus an extra top and bottom bollinger bands with a 2.5 standard deviation.
The users can use Stochastic Levels on Chart along with a simple Stochastic or a Stochastic Rsi indicator, when the price on chart touching extreme levels and Stochastic or Stochastic Rsi K line crossing above or bellow D line users can see on chart the levels where price need to close for getting stochastic overbought or oversold.
In the demo chart we can see at daily stochastic crossed down and the price crossed down all the levels displayed on chart, and same before stochastic was crossing up from oversold and price crossed up the stochastic levels displayed on chart.
In strong bullish moves the Extreme level 100 of the stochastic will be pushed higher, same in a strong bearish move the Extreme Oversold 0 level will be pushed lower, so users need to wait for confirmation of a crossover between K and D lines of stochastic that will signalize a pullback or a reverse of the trend.
For better results you will need to add a dmi or an adx or other indicator that will show you trend strength.
If you have any questions or suggestions to improve the script please send me a PM.