Typescript error runtime error: Cannot read property 'prototype' of undefined when extending

Question

So I\'m getting the above error in the console. It\'s caused by _super being undefined when it\'s passed to __extends (in the generated .js

Answer 1

I had the same problem and it was caused by export default statements. To fix it I simply removed those and imported the required items another way:

BEFORE

A.ts

export default MyClass;

class MyClass { ... }

B.ts

import MyClass from "./A";

class MyClass2 extends MyClass { ... }

AFTER

A.ts

export class MyClass { ... }

B.ts

import { MyClass } from "./A";

class MyClass2 extends MyClass { ... }