javascript - ES6+ javascript 模块导出选项

Question

我见过通过以下两种方式完成 ES6 模块的公共(public)导出:

// method 1
export var getAnswer = function () { return 'forty two'; };

// method 2
export default function () { return 'forty two'; };

1. 这两个都有效吗？
2. 如果是，为什么它们都存在？
3. 使用 ES6 语法是否有其他有效的模块导出选项？

我很惊讶我无法用我的 googlefu 找到答案。我只关心 ES6 模块，不 CommonJS、RequireJS、AMD、Node 等。

Answer 1

一年多以后，这里是我找到的有关该主题的最佳信息。

导出有 4 种类型。以下是每个的用法示例，以及一些使用它们的导入:

导出语法

// default exports
export default 42;
export default {};
export default [];
export default (1 + 2);
export default foo;
export default function () {}
export default class {}
export default function foo () {}
export default class foo {}

// variables exports
export var foo = 1;
export var foo = function () {};
export var bar;
export let foo = 2;
export let bar;
export const foo = 3;
export function foo () {}
export class foo {}

// named exports
export {};
export {foo};
export {foo, bar};
export {foo as bar};
export {foo as default};
export {foo as default, bar};

// exports from
export * from "foo";
export {} from "foo";
export {foo} from "foo";
export {foo, bar} from "foo";
export {foo as bar} from "foo";
export {foo as default} from "foo";
export {foo as default, bar} from "foo";
export {default} from "foo";
export {default as foo} from "foo";

导入语法

// default imports
import foo from "foo";
import {default as foo} from "foo";

// named imports
import {} from "foo";
import {bar} from "foo";
import {bar, baz} from "foo";
import {bar as baz} from "foo";
import {bar as baz, xyz} from "foo";

// glob imports
import * as foo from "foo";

// mixing imports
import foo, {baz as xyz} from "foo";
import foo, * as bar from "foo";

// just import
import "foo";

Source.