JavaScript导出语法之间有什么区别?

Question

我试图了解在javascript中导出组件的方式之间是否存在任何差异。我了解默认导出的工作原理以及如何导出变量，例如：

// when exporting a function:
export function foo () {}
// you can import it as
import {foo} from "foo";
// default export
export default class foo {}
//then:
import foo from "foo";

但我见过这样的案例：

export {foo as default} from "foo";
export {foo as default, bar} from "foo";
export {default} from "foo";
export {default as foo} from "foo";

有人可以解释一下default关键字在上述 4 种情况下的含义以及如何导入它吗？

Answer 1

// import foo and export it as default
export {foo as default} from "foo"; 
// import foo and export it as default
// import bar and immediately export bar
export {foo as default, bar} from "foo";
// import default as foo and export it
export {default as foo} from "foo"; 
// re-exporting the default export 
export {default} from "foo";

所有这些都是再出口，意味着进口东西并立即出口。