CODEWITHSUNDEEP
c#visual-studiovisual-studio-2013typescriptintellisense
xvdiff
xvdiff

Reputation: 2229

Typescript 'optional' (nullable) '?' syntax not working (partially)

I'd like to declare a number on a class as optional, using the '?' operator.

export class DummyClass {
    dummyId?: number;   
}

Visual Studio doesn't let me compile because of a '; is expected. Unexpected token' error. However when I e.g. declare a function or interface, it works without problems:

void(sup?: number) {} // nothing to complain here

Are there some rules about this? Or is something wrong with Intellisense?

Upvotes: 1

Views: 488

Answers (1)

Fenton
Fenton

Reputation: 250972

If you don't require that property to be set, you can just have:

export class DummyClass {
    dummyId: number;   
}

In this example, dummyId is undefined until someone sets a value. Essentially, properties need no special character to say "you don't have to set me".

When you accept an argument, you can make it optional. This is true of methods and constructors:

export class DummyClass {
    constructor(public dummyId?: number) {

    }


    doSomething(dummyId?: number) {

    }
}

Upvotes: 2

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