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I am using latest TypeScript and Angular and i have an object:

const obj: ObjInterface = { prop1: 1, prop2: 2, prop3: '3' }

Also i have interface based on that object:

interface ObjInterface { prop1: number; prop2: number; prop3: string; }

Is it possible to create interface of the array that consist only from properties of the obj?

const array: SomeInterface = ['prop1', 'prop2', 'prop3']; // OK const array: SomeInterface = ['prop1', 'prop2', 'prop4']; // error
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    Interfaces don't exist at runtime Commented May 7, 2018 at 9:38

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You can create an array of keys of a type using the keyof operator 

interface ObjInterface { prop1: number; prop2: number; prop3: string; } const array: Array<keyof ObjInterface> = ['prop1', 'prop2', 'prop3']; // OK const array2: Array<keyof ObjInterface> = ['prop1', 'prop2', 'prop4']; // error

Note This will be a compile time error, at runtime you can have different strings in the array if you venture outside the type system or if you use type assertions.

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