Nullish coalescing operator (??)

Returns the value on the right hand side if the value on the left hand side is null or undefined. Useful when you need to choose between a provided value or a default, but falsy values like 0 or '' are valid options.

> 0 ?? 'won\'t use this value'
0
> false ?? 'won\'t use this value'
false
> undefined ?? 'will use this value'
'will use this value'
> null ?? 'will use this value'
'will use this value'

Differs from || which returns the value on the right hand side if the value on the left hand side is falsy.

Source