Export default variable with BabelJS

Question

I'm using Babel for ES2015 module definitions.

I have a file a.js :

require('babel-core/register')({presets: ['es2015']})
require('./b')

Which requires a file b.js

export default b = () => true

Babel compiles this to

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});

exports.default = b = function Main() {
  return true;
};

But then throws an error:

ReferenceError: b is not defined
  at Object.<anonymous> (b.js:1:16)

Answer 1

I believe the issue comes from babel adding strict mode as you are then referencing an undeclared variable. Changing it to:

const b = () => true
export default b;

fixed it for me.

Answer 2

如果这是整个模块，并且没有全局b ，则这是运行时错误，因此这可能是第一个问题：

export default b = () => true