To handle these cases, you have a couple options. Please show your love and support by sharing this post.Objects can be a bit frustrating when using the typeof operator because typeof returns 'object' for both null and. However, if the type of the object is already known, then you can use " keyof" directly on the type, for example, like so: Error: 'person' refers to a value, but is being used as a type here. If you do that, you will get a compile error, such as the following: Using the keyof operator alone won't work in this instance, because it cannot be used directly on a value. In either case, the resulting type from using " keyof typeof" together will be a union of the string literals that represent the property names of the object, which in this case results in the union type, "name" | "age" | "status". Type PersonProps = keyof typeof person // "name" | "age" | "status" Type PersonProps = keyof Person // "name" | "age" | "status"Īlternatively, you can use " keyof typeof" to get the type of the object and its property names in one step like so: You can get the type of the " person" object using the " typeof" operator, and then use the " keyof" operator on the result to get all its property names: In the case where the type of an object is not directly known, you can use " typeof" to get the type of the object and then use " keyof" on the resulting type. Please keep in mind the distinction between values and types when using TypeScript. " keyof" operator works on the resulting object type and provides a union of all string literals that make up its property names." typeof" operator works on a JavaScript value (such as a variable, constant, parameter, function, class declaration, or enum) to infer the type of the value, and.When used together, " keyof typeof" can be used to get the property names of an object in TypeScript, where:
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