Hi - I recall seeing posts on this in the past; did you check out these posts?

JavaScript for Reaction Times (trouble producing full string of RTs in Embedded Data) | XM Community (qualtrics.com)

Recording reaction time with space bar (but for text entry NOT multiple choice) | XM Community (qualtrics.com)

I have read these and other posts, but these are too detailed tests. I need a simpler version (a box that changes colour and a click with a mouse to record the time). However, I  have no clue where to start as I am new to Java and Qualtrics. 

I made a simple reaction time question, so answering is no longer needed. 

Good afternoon from a sunny Sweden!

Want to share how you solved it? I’m always looking to learn :)

I am looking to do the same thing, can you share how you did it? Thanks!