Variable assignment bitwise or in Javascript

Question

I ran into a code in Javascript like this:

is_enabled = is_enabled | true;

What does it intend to do? To me it seems doing nothing.

Answer 1

I think the code you are referring to is:

is_enabled = is_enabled || true

This allows the variable is_enabled to be defined elsewhere in the code. So, is_enabled's value is either it's previous definition, or if it has not been declared, it is true.