SystemJS on ready?

Question

Is there a way to wait until all System.registers (transpiled from ES6) are resolved and loaded?

This is especially useful for e2e testing in Angular and other little things.

Answer 1

System.import the module you want to wait for which returns a promise.

System.import("myModule").then(function() {
   // here it is loaded.
});

In practice, you probably want to use something like systemjs-builder with route specific bundling logic rather than load things with system on the first page load - so less round trips are made to the server.

Answer 2

The Problem with System.import().then is that the second-level dependencies will not get resolved.

System.register has a "callback" that is executed when all its dependencies (and dependencies of its dependencies, etc. ) are resolved.

When transpiling from ES6, basically this "callback" constructed from the rest of the code in the file—all the code expect the import statements. Therefore, I don't really have to do anything with SystemJS to get a callback to start the tests; the problem is now how to get testing, i.e. Protractor, to start manually. Currently, the workaround is to delay the testing by a fixed ~30 seconds.