Your 'this' doesn't reference to window, causing errors in strict environment.

[indigo-sam]

(function (root, factory) {
if (typeof define === "function" && define.amd) {
// AMD - registered as an anonymous module
define(factory);
} else if (typeof exports === "object") {
// CommonJS
module.exports = factory();
} else {
// Browser global
root.objectFitPolyfill = factory();
}
})(this, function () {... //'this' in a strict environment would reference to 'undefined' thus creating an undefined error.

[cee-chen]

Could you please confirm (and preferably take screenshots) of any errors being thrown?

The above code is a very common Universal Module Definition pattern for Javascript modules. I would strongly prefer not to change a pattern that isn't mine, since this changes depending on whether the environment is the browser, Node, etc (more info in this Stackoverflow discussion and also this article).

[indigo-sam]

Oh that would make sense if they use the plugin in Node to reference different object. I was using babel and it automatically add a global 'use strict'. The 'this' would be forced to be an undefined instead of window object, but I see why it should be 'this' instead of window now. I guess I have to use different babel preset plugin to turn off global 'use strict'.

[cee-chen]

Thanks Sam! Looks like if you're using Babel 6, you can just not include the strict-mode plugin. This Stackoverflow question might help? :)