Coronal jet intensity curves for data set 1 (without threshold—bottom curves) and data set 2 (with threshold—top curves) in the top panels (CJ1) and (CJ2/CJ3/CJ4). Red (data set 1) and blue (data set 2) solid-line parts of the curves indicate precursors events. Accordingly, we plot zooms of these parts in the detrended form in the bottom panels (CJ1), (CJ2), (CJ3), and (CJ4), respectively. Panels (CJ1; top and bottom) correspond to the case of the single CJ that started at 2015 December 9 17:28 UT with a precursor start approximately 9.8 minutes before the CJ release. While panels (CJ2/CJ3/CJ4), (CJ2), (CJ3), and (CJ4) demonstrate the case of the recurrent CJs that started at 2015 December 30 23:16 UT, which includes three subsequent plasma ejections. Each of them has precursors starting 19.6, 7.8, and 5.6 minutes before the respective CJs. Vertical dashed lines represent the end of precursor ignition.