最小的承诺/ A +承诺界面

Question

I am writing a JavaScript code generator and want to avoid a dependency to a specific Promises/A+ framework. Instead of using callbacks in methods/functions, I want to return promises.

What is the minimal required interface of a promise object so that it works with any Promises/A+ library?

Answer 1

The only required interface for a Promises/A+ is implementing the then method.

This is specified here: http://promisesaplus.com/

This makes sense, since A+ is only about making promises interoperability , as a standard it only specifies the bare minimum for that.

You can .catch with:

promise.catch(err){

});
// is the same as the following, which is required by the Promises/A+ standard.
promise.then(null, function(err){

});