Detecting the count of values in a JavaScript variable

Hello!
I am currently running an intercept survey on our website using Website / App Feedback. The intercept is embedding a Javascript variable that can have 1 or more values and is passing that variable to the survey.
I'd like to create a new variable/field in the survey that counts the number of values in the embedded field for each respondent.
For example: Perhaps the questionnaire is surveying fast food customers after placing an online order. The intercept embeds a JavaScript variable called

condiment

which can have the values

ketchup

mustard

and/or

mayo

. In this case, I would like to create a new variable that counts the number of condiments for each respondent. So, if someone had ordered ketchup, mustard, and mayo, the new variable would return

3

, if just ketchup, it would return

1

and so on.
Is this possible?
Thanks so much for your help and generosity!