Menu
Asking for help, clarification, or responding to other answers.
The question mark after the variable is called Optional chaining (?.) in JavaScript. The optional chaining operator provides a way to simplify accessing values through connected objects when it's possible that a reference or function may be undefined or null.
Yes, the "?:" operator will return the value to the left, if it is not null. Else, return the value to the right. "Yes, the "?:" operator will return the value to the left, if it is not null." - That is incorrect.
?. is a null safe operator which is used to avoid unexpected NPE.
if ( a?.b ) { .. }
is same as
if ( a != null && a.b ) { .. }
But in this case is() is already null safe, so you would not need it
other.is( this )
should be good.
There is a subtlety of ?., the Safe navigation operator, not mentioned in @dmahapatro's answer.
Let me give an example:
def T = [test: true]
def F = [test: false]
def N = null
assert T?.test == true
assert F?.test == false
assert N?.test == null // not false!
In other words, a?.b is the same as a != null && a.b only when testing for a boolean value. The difference is that the first one can either evaluate to a.b or null, while the second one can only be a.b or false. This matters if the value of the expression is passed on to another expression.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With