The logical operator "nullish coalescing" (
??) is a way of saying you want to use one value OR another value. If the first value is null or undefined, you'll use the right side of the operator. Otherwise, you'll use the left side. This is where it differs from the OR operator, but it's very closely related.
For more information on the logical nullish coalescing operator, read this documentation.
Just a heads up
The nullish coalescing operator is new, and may not be available everywhere. It is available to use in most browsers (CanIUse nullish coalescing operator) but make sure you double check that it's available where you need it before using it.