How can I covert this SQL query into Sequelize syntax?

[bryceremick]

I've looked at the docs, but I'm still not sure how to convert this to Sequelize syntax:

SELECT challenges.* 
FROM challenges 
LEFT JOIN participants 
ON challenges.id = participants.challengeId 
WHERE challenges.userId = 2002 
OR participants.userId = 2002;

The ON clause is throwing me off.

Can anyone point me in the right direction?