[TypeScript] Represent Non-Primitive Types with TypeScript’s object Type

ypeScript 2.2 introduced the object, a type that represents any non-primitive type. It can be used to more accurately type methods such as Object.create. Don't confuse it with the Object type or {}, the empty object type, though!

So one thing we need to understand that the Primitive types includes: 'number, boolean, string, symbol, null, undefined'. The 'array, {}, fn()' belongs to 'object' type. The 'object' type therefore is different from 'Object' type in typescript. 'Object' type is referring empty object ( {} ).

Type 'Object' gives autocomplete. It includes all the methods which an empty object can have.

But empty object without Object type has not.

If we try to assign a value to empty object, we get error:

In order to do it, we can do:

const object: { [key: string]: any } = {};
object.foo = 'bar';