The rules for Bonus Actions (PHB, pg.189) state;
You can take only one bonus action on your turn…
Which to me can be read in two ways.
- You can only take a bonus action if it is your turn.
- You can take only one bonus action on your turn but can take one or more on someone else’s turn.
As an example, if I were to ready an attack action could I also use a bonus action for Two-Weapon Fighting when the trigger is met?