TypeScript dynamic object properties

Question

In TypeScript, it is possible for a type declaration to allow for dynamic object properties?

class Animal {
    name: string;
    [everything else]: any;
}

let animal = <Animal>{ name: "Kitty", type: "cat" };

animal.name; // Would be treated as string

animal.type; // Would allow compilation and be treated as any

I would like these extra properties to be allowed dynamically, without having to add them to the type declaration. Using TypeScript 1.8.2.

Brian Pfretzschner · Accepted Answer · 2016-03-09 10:15:58Z

1

Yes, like this:

class Animal {
    name: string;
    type?: any;
}

But I would suggest using an Enum for type like this:

enum AnimalType {Cat, Dog, ...};

class Animal {
    name: string;
    type?: AnimalType;
}

edited Mar 9, 2016 at 10:15

answered Mar 9, 2016 at 10:13

Brian Pfretzschner

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4 Comments

MichaelAttard Over a year ago

What about colour for example? I want the extra properties to be allowed without having to add them to the type.

Brian Pfretzschner Over a year ago

This should not give an error at all: See typescriptlang.org/…

MichaelAttard Over a year ago

It does. typescriptlang.org/…

Brian Pfretzschner Over a year ago

I think you have to use it similar to a map but I am not sure if that is a good idea: typescriptlang.org/…

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