The Data Layer

Looking at the Google tracking code for global site tag I was curious about the syntax ||.

|| in Javascript is a Logical OR.

What Google Developers webite says

A data layer is a JavaScript object that is used to pass information from your website to your Tag Manager container. You can then use that information to populate variables and activate triggers in your tag configurations. ... Transaction data: Cart value, checkout date. Customer information: New or returning customer.

Links

External Sources

The Data Layer