Not much special about this script; you can use date & time, or bar count, to ascertain the number of bars in a time period for backtesting.
This script can be used in conjunction with large scripts incorporating complex intricacies that won't load on 20,000+ bar data sets.
If your script's load time transcends the TV allotted load time - use this script to quickly determine the number of bars in the data set.
Through trial & error you should be able to determine the approximate number of bars your script can execute on without exceeding the imposed time limit!
The image above shows a user-defined time window and, consequently, the script returns the number of bars that constitute the time period.
You can drag the white vertical lines to efficiently configure the calculated time period.
The image above shows functionality for the "Bars Back" feature.
•Discord Server: discord.gg/3cKVU28Z9Z
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.