Uptrend - RSI > 60
Downtrend - RSI < 40
Sideways - RSI between 40 and 60
If however not interested in filtering for sideways trends and convert it to a long-short only strategy that stays in market all the time then it can be simply modified by setting both overbought/oversold thresholds to 50. In such a case uptrend will be above 50 and downtrend will be less than 50.
Note: wait for close for current bar to be confirmed as RSI is calculated at close
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.