Execute Code after firestore get method is finished

I know that using java (android) you can execute code after the get method is finished, is that also possible when using javascript?

Here is my code:

      mColRef.get().then(function(querySnapshot){
          querySnapshot.forEach(function(doc) {
              console.log(doc.id);
          });
      });

Can I do something like this? Or how would you code something like this for web (javascript)?

     mColRef.get().then(function(querySnapshot){
          querySnapshot.forEach(function(doc) {
              console.log(doc.id);
          });
      }).OnCompleteListener(new OncompleteListener ....

Thanks for your help!