TS2550

Property 'setPrototypeOf' does not exist on type 'ObjectConstructor'. Do you need to change your target library? Try changing the 'lib' compiler option to 'es2015' or later.

Broken Code ❌

type HumanHero = typeof human & typeof hero;
 
const human = {
  speak: () => {},
};
 
const hero = {
  fly: () => {},
};
 
// Prototype-based inheritance
Object.setPrototypeOf(hero, human);

{
  "compilerOptions": {
    "lib": ["dom", "es5"],
    "target": "es6"
  }
}

Fixed Code ✔️

ES5, also known as ECMAScript 2009, doesn't include Object.setPrototypeOf which is why you have to upgrade to ES6 (also known as ES2015):

{
  "compilerOptions": {
    "lib": ["dom", "es6"],
    "target": "es6"
  }
}