A look at the history, current state, and hopeful future state of script loading in browsers.

1. T he O nce and F uture S cript L oader Kyle Simpson @getify http://getify.me

2. where…we were once upon a time, in a browser far, far away…

3. <script src=&quot;…&quot;></script> where…we were

4. <script src=&quot;…&quot;></script> <script src=&quot;…&quot;></script> <script src=&quot;…&quot;></script> <script src=&quot;…&quot;></script> <script src=&quot;…&quot;></script> <script src=&quot;…&quot;></script> … where…we were

6. <script> tags block. bad. evil. where…we were

8. IE7-, FF3-, Opera where…we were

9. IE8, FF3.5/3.6, Chr 14- where…we were

10. IE9+, FF4+ Script Loaders where…we were

11. document.write() where…we were

12. document.write() Must Die! where…we were

14. The very first script loader? document.write(&quot;<script src='...'></sc&quot;+&quot;ript>&quot;); where…we were

15. w ho- tf ? ...and still many ad providers, 3rd party widgets, etc. where…we were

16. Surely we can do better!? where…we were

17. XHR? where…we were

18. Framework-specific loaders... ...just stink where…we were

19. Making progress... but not there yet where…we were

20. What's hard about script loading? where…we were

25. <script> tags (even dynamically created) give you no control over loading or execution where…we were

26. The spec says that dynamic scripts should load and run ASAP (not ordered) umm... where…we were

27. All current browser versions except Opera (but soon!) follow the spec uh oh where…we were

28. Some older browsers execute in order, some don't doh! Some older browsers load in parallel, some don't where…we were

29. Not for the faint of heart where…we were

30. A young leader? LABjs where…we were

31. LABjs: performance script loader where…we were

32. where…we were LABjs: performance script loader

34. Anyone can write a loader! where…we are now (and many devs have)

35. where…we are now https://spreadsheets0.google.com/spreadsheet/ccc?key=tDdcrv9wNQRCNCRCflWxhYQ

36. Loaders are competing more on APIs than on features or performance where…we are now

37. They're also copying each other (good and bad) where…we are now

38. But, can their functionality be trusted? where…we are now

39. Testing is much harder than most realize where…we are now

40. &quot;Browser support&quot; is vague where…we are now

41. Exception cases often ignored or overlooked where…we are now

42. Browser Sniffs, Hacks where…we are now

43. What should a loader do? where…we are now

44. Real Preloading http://wiki.whatwg.org/wiki/Script_Execution_Control where…we are now

45. IE4+ ftw? where…we are now

46. async=false http://wiki.whatwg.org/wiki/Dynamic_Script_Execution_Order Ordered Async FF4+, Chr 12+, IE10p2+, Webkit/Safari, Opera (soon!) where…we are now

49. What happens next? where…we're going next

50. Competition is good, only if community is educated where…we're going next

51. http://Pick A Loader.com where…we're going next (coming soon)

52. Browsers do not yet give us what we really need where…we're going next

53. Co-opetition is much healthier for the community where…we're going next

54. Only script loaders which help build the future will survive where…we're going next

55. W3C, WHATWG http://wiki.whatwg.org/wiki/Category:Proposals where…we're going next

56. We'll accomplish more if we work together where…we're going next

57. Future, The Script Loader where…we're going next

58. Preloading (deferred execution) where…we're going next

59. Modules (CommonJS, AMD, etc) where…we're going next

60. Native Modules (ES-Harmony?) where…we're going next

62. &quot;Script Loader of my dreams&quot; where…we're going next

64. And now for something completely different... Questions?

65. http://pickaloader.com Kyle Simpson @getify http://getify.me http://labjs.com http://wiki.whatwg.org/wiki/Category:Proposals