I have one question. Help me, please.
I have code in my teaching proggram:
alert(user.address ? user.address.street ? user.address.street.name : null : null);
But I can't understand, why he used "null" two times at the end of the code?
I understand that if user.adress - exist, then check whether user.address.street exist, if user.address.street - exist, then check whether user.address.street.name exist, if not alert - null.
But why did he write second null?
The ? operator is a shorthand for an if-else assignment.
alert(user.address ? user.address.street ? user.address.street.name : null : null);
Is the short form for:
let res;
if (user.address) {
if (user.address.street) {
res = user.address.street.name;
} else {
res = null;
}
} else {
res = null;
}
alert(res);
In javascript there is also the 'optional chaining operator' which is probably what you want:
alert(user?.address?.name);
Which only access the objects properties if they are not null, otherwise returns null.