ES6+ javascript module export options

Question

I've seen public exports of ES6 modules done in both of the following ways:

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

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

1. Are both of these valid?
2. If so, why do they both exist?
3. Are there other valid options for module exports using ES6 syntax?

I'm surprised I haven't been able to find the answer with my googlefu. I'm concerned only with ES6 modules, not CommonJS, RequireJS, AMD, Node, etc.

Answer 1

A year and some later, here is the best information I've found on the subject.

There are 4 types of exports. Here are usage examples of each, along with some imports that use them:

Export Syntax

// 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";

Import Syntax

// 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.