Typescript Javascript one line If…else…else if statement

Question

I have this piece of code:

 if (service.isHostel) {
            return new Hostel({url: service.url});
        } else {
            return new booking({url: service.url});
        }

that I want to express in 1 line,

service.isHostel ? Hostel({url: service.url}) : return new booking({url: service.url})

but I have a compilation error:

Expression expected.

Try return service.isHostel ? new Hostel({url: service.url}) : new booking({url: service.url}) — Hao Wu
– Hao Wu, Commented Feb 3, 2020 at 8:14
the whole code should be return return service.isHostel ? new Hostel({ url: service.url }) : new booking({ url: service.url }); — user11537130
– user11537130, Commented Feb 3, 2020 at 8:16

Maheer Ali · Accepted Answer · 2020-02-03 08:15:59Z

2

You can only write expressions(piece of code which returns are value) inside ternary operation. return is a statement which can't be used inside the expression of ternary operators.

Here you have to return both the values you can use return before ternary

return service.isHostel ? new Hostel({url: service.url}) : new booking({url: service.url})

answered Feb 3, 2020 at 8:15

Maheer Ali

36.5k8 gold badges53 silver badges83 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Nina Scholz · Accepted Answer · 2020-02-03 08:19:47Z

2

You need to add a new operator as well for Hostel and omit the return return statement inside of the ternary.

return service.isHostel ? new Hostel({url: service.url}) : new booking({url: service.url});

Another version is to choose different classes.

return new (service.isHostel ? Hostel : booking)({url: service.url});

edited Feb 3, 2020 at 8:19

answered Feb 3, 2020 at 8:15

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

1 Comment

Ayush Gupta Over a year ago

I like this method because if you move (service.isHostel ? Hostel : booking) to a seperate function, you arrive at the factory pattern

Collectives™ on Stack Overflow

Typescript Javascript one line If…else…else if statement

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related