环境变量未分配Typescript

Question

我的代码是：

const port: Number = process.env.PORT || 3000;

[ts]
Type 'string | 3000' is not assignable to type 'Number'.
  Type 'string' is not assignable to type 'Number'.

我试过

const port: Number = parseInt(process.env.PORT, 10) || 3000;

但它给了我另一个错误：

Argument of type 'string | undefined' is not assignable to parameter of type 'string'.
  Type 'undefined' is not assignable to type 'string'.
(property) NodeJS.Process.env: NodeJS.ProcessEnv

我做错了什么？

Answer 1

const port: Number = parseInt(<string>process.env.PORT, 10) || 3000

这解决了它。我认为它被称为Type Assertion

Answer 2

这也应该有效。

const port: Number = parseInt(process.env.PORT as string, 10) || 3000