模块加载器规范和导入/导出语法是分开的。所以这是模块加载器的属性（不是ES规范的一部分）。如果您使用支持诸如 SystemJS 的插件的模块加载程序。

Is it possible to import javascript module from external url in ES6?

I tried (using babel-node):

import mymodule from 'http://...mysite.../myscript.js';
// Error: Cannot find module 'http://...mysite.../myscript.js'

The module loader spec and the import/export syntax are separate. So this is a property of the module loader (not a part of the ES spec). If you use a module loader that supports plugins like SystemJS.