gorshkov-leonid/typescript-tricks.md

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typescript-tricks.md

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typescript-tricks.md

Tricks with types

Typesafe Object.keys

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declare global {
    // https://github.com/microsoft/TypeScript/issues/3889
    type ObjectKeys<T> = T extends object
        ? (keyof T)[]
        : T extends number
        ? []
        : T extends Array<any> | string
        ? string[]
        : never;

    interface ObjectConstructor {
        keys<T>(o: T): ObjectKeys<T>;
    }
}


const a: MyType = {
  id: '',  
  name: ''
};
Object.keys(a).forEach((key) => {
    // typeof key = 'id' | 'name'
    console.log(a[key]);
});