import()ed module is not executed until .then() or .catch() is called on it

// globalHaCKS.js

window.document.stateOverride13 = 'YOLO';

renderLegacyApp();

// just_make_it_less_slow.js

import('./globalHaCKS.js'); // Doesn't work!

import('./globalHaCKS.js').then(); // Works :s

When using webpack’s built in support for the import() statement, the imported module is executed as soon as the promise is created and the chunk is downloaded. With this package, it seems that the imported module is executed only when .then() or .catch() is called on the promise (even though either way the chunk is downloaded as soon as the promise is created).

This seems like an unnecessary and confusing breaking change compared to the way import() works in webpack. Any chance of changing it so that it is not necessary to call .then() or .catch() on the promise?

[ScriptedAlchemy]

This is something that’s been documented in the caveats.

Check out the Babel plugin readMe

Pretty much, you are not using a normal import function which webpack provides. It’s transformed into our universalImport

While it is thennable, it’s not self evoking. “Then” in our context, is a function which executes “load”, which is a promise.

Give this a read: https://github.com/faceyspacey/babel-plugin-universal-import/blob/master/universalImport.js ——— To the discerning eye, you may be wondering if the return of import() is still thenable?? It is! However, if you don’t call .then on it, somewhere (perhaps in the components like react-universal-component that you pass it to), then it won’t perform the import. Since most of us are using modules, which we need to do something with in the then callback, that’s not a problem. But if you happen to be importing a module that does its own setup, such as attaches something to the window object, well then you just need to call .then() to trigger it. That’s a rare case these days, which is why we decided to go with the simplicity seen here. And yes, async await works too.

[faceyspacey]

Thanks @zackljackson …couldn’t have explained it better. Hope that helps @hedgepigdaniel