Add callback to 'end' event handler

[andyjansson]

Currently, it's not possible to perform asynchronous operations within the end event and manipulate the resulting CSS based on these operations. This causes a lot of problems since node.js and its ecosystem is primarily asynchronous. To mitigate this problem, I propose that a callback should be added like we once had in versions prior to 0.40.0, e.g.:

stylus.on('end', function (css, callback) {
    someAsynchronousOperation(function (err, result) {
        if (err) callback(err);
        callback(null, result); 
    });
});

In case of multiple listeners, it could move to the next listener after the callback has been triggered to not cause any issues with asynchronous writes to the CSS.

[madeleineostoja]

+1 this is a big problem for me with https://github.com/seaneking/poststylus, to process asynchronous PostCSS plugins we need to pass the result back to end in a callback.

[j-walker23]

Hi guys, is this still broken? I am trying to figure out a way to use stylus as es6 imports in a jspm systemjs app. Would this bug prevent me from doing that?
Thanks for any help!

[Panya]

@j-walker23 well, first of all it's not a bug. The issue is about support for asynchronous plugins inside end event handlers (so it's enhancement).

Hi guys, is this still broken? I am trying to figure out a way to use stylus as es6 imports in a jspm systemjs app. Would this bug prevent me from doing that?

Node.js version of Stylus heavily using fs for imports and some built-in functions and can't be used as-is for the browser. But we have special client branch for client-side usage. Information in this issue may help you acheive your goal.

[j-walker23]

Thanks for the help @Panya, i appreciate it!

[sugarshin]

👍

[FezVrasta]

Any update on this? it's quite important to make PostCSS work with Stylus 😕