Timing promises

I have a deeply nested loop of promises that query a remote API, and I had them logging their time by default, like this:

jcm: 1745ms
jcr: 1765ms
jcl: 1935ms
je: 1750ms

Since a few weeks though, as the number of API requests grew, the output got so log that the message was being clipped by GMail. Today I thought I would review the logging and trim it a bit.

I had the timing code in a utility function interwoven with the other async flow control code, and now it was time to get it out of there. That code was pretty dense by itself, so I scratched my head a bit, but then I realized that it’s promise-based, and so I just cut the timing code out and wrote a little utility function that given a promise and a label, returns the same promise and logs its duration:

function time(promise, label) {
  label = label.toString();

  return promise
  .then(function(response) {
    return response;

Now I can use it to only time things that I want. I have another function that retrieves some data from a Firebase, and I wanted log that too:

ClientLists.get = function() {
  return getFirebaseData('/data')

to log its duration I changed it to:

ClientLists.get = function() {
  return time(getFirebaseData('/data'), 'getting client lists')

and now I get a nice timing log:

getting client lists: 1740ms

Nice! Now my log is nice and tidy.