Randomly intersperse attention checks at the end of a repitition

[jackransomlovell]

Hi everyone, I am struggling to solve a problem related to attention checks, and if anyone has advice I would greatly appreciate it! So I have a trial with a couple of parameters, and I repeat that trial 13 times. I would like to randomly place an attention check at the end of a trial.

So let's say for participant 1 there's an attention check at the end of trials: 2,6,9
For participant 2 there's one at the end of trials: 1,7,12
etc..

My current code is as follows:

var trial = {...}, // trial obj var attn_check = {...}, // attention check var sequence = { timeline: [trial], repetitions: 13} // sequence timeline.push(sequence)