Chris Heilmann gave a talk about breaking out of endless callback loops in JavaScript development. He discussed the history and evolution of JavaScript, including its growing capabilities and uses. However, he emphasized that progressive enhancement and capability testing are still important principles on the client side to avoid broken experiences. While tools like transpilation and polyfills can help bring future features to current browsers, overreliance on them has downsides. The best approach is to embrace JavaScript's use in different environments and balance innovation with backward compatibility.

1. BREAKING OUT OF THE
ENDLESS CALLBACK LOOP
CHRIS HEILMANN (@CODEPO8), JSDAY 2015, VERONA, ITALY

2. @codepo8
Chris Heilmann

3. @codepo8
Chris Heilmann• Web Developer since ~1997
• Wrote first book about JavaScript
*and* AJAX ten years ago.
• Delivered many large projects,
including Yahoo Search, Maps
• Worked on YUI
• Worked on Firefox OS
• Now working at Microsoft
helping with the most important
change the web needs

4. BACK TO MY OLD
HAUNTS…

7. JAVASCRIPT IS THE
HOT THING RIGHT
NOW!
SO, WELL DONE, YOU
CHOSE THE RIGHT EVENT.
(PROMOTIONS ALL AROUND)

8. BEING WANTED IS A
GREAT FEELING.

9. WITH A LOT OF
EXCITEMENT AND
DEMAND ALSO
COMES A LOT OF
STRESS.

10. IT IS EASY TO GET
THE IMPRESSION
THAT YOU’RE
FALLING BEHIND.

11. ++CALM;

12. --WORRY;

15. JAVASCRIPT IS…
• An incredibly versatile
language
• Available web-wide and
across many platforms
• Toolset independent
• Forgiving and inviting

16. YOU CAN USE
JAVASCRIPT…
• In browsers on the web
• On the server
• In applications
• To access services
• As a data format (JSON)
• On hardware
• … your turn, surprise me :)

17. ALLOW ME TO
TAKE YOU BACK
IN TIME FOR A
MOMENT…

18. WHEN CHRIS MET
JAVASCRIPT…
• Form validation
• Image rollovers
• Popup windows (with dynamic
framesets and inter-window
communication)
• DHTML (document.all or
document.layers?)

19. !PLAYTIME
http://www.onlinetools.org/articles/unobtrusivejavascript/

20. WHEN THINGS GOT
INTERESTING… • Standardised DOM
• Event Model
• Development Tools (Firebug,
Error Console)

21. WHEN WE STARTED
BREAKING THE
WEB PROPERLY… • AJAX
• Library Wars
• Framework Dependencies
• Fixing browser problems with
shims and libraries

22. THINGS THAT
NEVER CHANGED…
(AND STILL ARE THE SAME)
• JavaScript is *not* fault tolerant
like CSS or HTML are
• JavaScript should be used as
an enhancement of sturdy,
semantically valuable and
working web content
• JavaScript can not be trusted
to be available
• Not all browsers are born
equal.

23. BACK TO THE
NOW…

24. OUR
DEVELOPMENT
ENVIRONMENT IS
INCREDIBLE!
• Developer tools in browsers are
outstanding and give us incredible
insights.
• We can debug across devices and
even convert HTML5 to native apps
for closed systems (manifold.js/
volon.js).
• Editors have linting, build integration,
and some are even written in
JavaScript and run in the browser.
• We share code on GitHub and help
debug problems using JSFiddle,
JSBin and others…

25. ALAS…

26. ON THE CLIENT,
PROGRESSIVE
ENHANCEMENT IS
STILL YOUR BEST
BET!

27. CAPABILITY
TESTING MEANS
YOU NEVER
DELIVER BROKEN
EXPERIENCES.

28. “CUTTING THE MUSTARD”
https://justmarkup.com/log/2015/02/26/cut-the-mustard-revisited/

29. SETTING YOUR BASELINE…

30. EXTENDING THE BASELINE

31. CAPABILITY
TESTING ALSO
ISN’T BULLET
PROOF…
• False positives are possible
• You can’t assume that support of
one feature means another also
works
• Experimental technology is hard to
test for
• You need to stay up-to-date

32. WHAT ABOUT
POLYFILLS?

33. POLYFILLS ARE
GREAT…
• Building solutions now using tech of
tomorrow
• Allowing developers to write code
now without waiting for standards
bodies to catch up
• Fixing browser inconsistencies
during the adoption period
• Allowing developers to concentrate
on the solutions rather than the tech
that enables them

34. POLYFILLS ARE
NOT SO GREAT…

35. POLYFILLS ARE
NOT SO GREAT…
• We become dependent on them
• They give performance hungry
functionality to outdated
environments
• They need to keep up with changes
in the specs, too.
• They tend to stay in non-maintained
projects and add to the landfill of
unnecessary JS.

36. POLYFILLS AS A
SERVICE!
https://cdn.polyfill.io/v1/docs/

37. IF YOU’RE NOT ON
THE WILD, WILD
WEB IN A CLIENT -
GO NUTS!
• JavaScript in a fixed, defined
environment (app platform,
add-ons, plugins)
• JavaScript server-side
• JavaScript as a conversion
target

38. BUT, WHAT ABOUT
THE FUTURE OF
JAVASCRIPT?

39. “JAVASCRIPT HAS A
HYPE-FUELLED
COMMUNITY.”
https://www.youtube.com/watch?v=6tgbrN0vyec
ES6 vs Today by Andrea Giammarchi @ FEDLondon

40. WE’RE VERY
EXCITED ABOUT
EVERYTHING…
• If it is new, it must be better!
• We want to have it now, maybe
even yesterday.
• A use case will come, let’s just
build the thing first.
• If there isn’t a problem, let’s
come up with one.

41. https://medium.com/@PitaJ/the-most-convoluted-api-40d8f7bc4176

42. THIS IS TOTALLY OK
AND VERY
NECESSARY.
(AND THIS EVENT IS FULL
OF CONTENT LIKE THIS)

43. LET’S BE INSPIRED
INSTEAD OF FRUSTRATED
BY THESE THINGS…
WE’RE PREPARING FOR
THE FUTURE.

44. WHAT IF
CAPABILITY
TESTING IS NOT
ENOUGH?

45. ES6 AND NEWER
VERSIONS OF THE
LANGUAGE HAVE
SYNTAX CHANGES.

46. ES6 SUPPORT IN THE WILD…
http://kangax.github.io/compat-table/es6/

47. HELP TESTING!
https://github.com/tc39/test262 http://test262.ecmascript.org/

48. WE COULD START
WITH A LANGUAGE
THAT CONVERTS
TO ES5…

49. WE CAN ALSO
TRANSPILE TO
ES5…

50. FORCING THE
FUTURE?
• We can use all kind of tricks to
make the JS capabilities of
tomorrow available today.
• The issue is that we’re
leapfrogging innovation - and
in some cases even slow down
native adoption.

51. FORCING THE
FUTURE?
• We run the danger of turning
our patches into
dependencies.
• We make resource hungry
code run in outdated
environments.

52. WHAT IF WE COULD
APPLY CAPABILITY
TESTING AND
TRANSPILE ON
DEMAND?

53. TESTING FEATURES, DELIVERING WIN.
https://featuretests.io/

56. BEST OF BOTH
WORLDS?
AND THAT FROM A MAN WHO
IS GOING TO TELL YOU TO
“BREAK THE BROKEN WEB” !

57. HERE’S THE
THING…
• The unknown client web is
what brought us here.
• It isn’t going to go away - it
would be terrible if it did.
• This doesn’t stop us from
innovating the language as we
have dozens of new paths to
use it.

58. THE TRICK IS TO
EMBRACE THE
FACT THAT
DESPITE USING
ONE LANGUAGE…

59. …WE WORK IN
DIFFERENT
ENVIRONMENTS
AND TOWARDS
DIFFERENT
GOALS.
• Adaptive and responsive web
sites
• Games
• Apps
• Servers
• Robots
• Drones
• …

60. IN THE END, WE ALL DELIVER TO OUR USERS…

61. AS FOR ME…

62. BY FAR THE #1
REASON I GOT FROM
WEB DEVELOPERS
NOT EMBRACING NEW
WEB TECHNOLOGY:
WE NEED TO SUPPORT
INTERNET EXPLORER!

63. AND I AM HAPPY TO
REPORT, THAT WE ARE
WELL ON THE WAY OF
MAKING THIS ISSUE
GO AWAY.
DEV.MODERN.IE

64. CLEANING UP IS A
VERY REWARDING
THING…

65. DO WHAT MAKES YOU
HAPPY - WITHOUT
HINDERING OTHERS IN
THE SAME ENDEAVOUR

66. Chris Heilmann
christianheilmann.com
@codepo8
GRAZIE!