Transpilation differences between create-react-app and sku

[David Porter]

There appears to be something somewhat different in the behaviour of the compilation of this and the create-react-app, where I consistently get my upstream auth0-js library's dependency reqwest failing due to an undefined this:

reqwest.js, as transpiled, looks like this:

!function (name, context, definition) {
  if (typeof module != 'undefined' && module.exports) module.exports = definition();
  else if (true) !(__WEBPACK_AMD_DEFINE_FACTORY__ = (definition),
        __WEBPACK_AMD_DEFINE_RESULT__ = (typeof __WEBPACK_AMD_DEFINE_FACTORY__ === 'function' ?
        (__WEBPACK_AMD_DEFINE_FACTORY__.call(exports, __webpack_require__, exports, module)) :
        __WEBPACK_AMD_DEFINE_FACTORY__),
        __WEBPACK_AMD_DEFINE_RESULT__ !== undefined && (module.exports = __WEBPACK_AMD_DEFINE_RESULT__));else context[name] = definition();
}('reqwest', undefined, function () {

// context here is undefined:
  var context = this;

// causing an error here, because it's attempting to access a property on an undefined object
  if ('window' in context) {
    var doc = document,
        byTag = 'getElementsByTagName',
        head = doc[byTag]('head')[0];
  } else {
    var XHR2;
    try {

Whereas, the working version has the this keyword set correctly, and looks like this I think:

!function (name, context, definition) {
  if (typeof module != 'undefined' && module.exports) module.exports = definition()
  else if (typeof define == 'function' && define.amd) define(definition)
  else context[name] = definition()
}('reqwest', this, function () {

  // context is window here
  var context = this

  if ('window' in context) {
    var doc = document
      , byTag = 'getElementsByTagName'
      , head = doc[byTag]('head')[0]
  } else {
    var XHR2
    try {
      XHR2 = require('xhr2')
    } catch (ex) {
      throw new Error('Peer dependency `xhr2` required! Please npm install xhr2')
    }
  }

• I don't see any tickets for this error on either the Auth0 library or Reqwest.
• config for the repo I'm working on is here

[Mark Dalgleish]

Looks like it's because the code is running through Babel, which is treating it as an ES6 module, where this is getting transpiled to undefined. I found a Stack Overflow issue with more details: http://stackoverflow.com/questions/34973442/how-to-stop-babel-from-transpiling-this-to-undefined

To fix this, we probably need to ensure that Babel ignores node modules.

[David Porter]

Yep, that's fixed it