Defensive Programming In JavaScript

20 Tips for defensive code. My experience writing defensive front-end javaScript for Server Density, specifically:

* Why defensive code should matter to you
* Lessons in defensive failures.
* Why you should be ruthlessly pragmatic about bugs.
* JavaScript and defending against type errors
* How your code can be more defensive today.
* Takeaways for the sceptics.

Transcript

1. @serverdensity @byrichardpowell
2. bit.ly/30TB-pm 30TB of data per month
3. Defensive Programming What shouldn't happen will happen.
4. “Defensive programming is … intended to ensure the continuing function of a piece of software under unforeseen circumstances. en.wikipedia.org/wiki/Defensive_programming
5. 1. You want robust software 2. You want easy debugging 3. You want to re-use code 4. You have an unpredictable environment 5. You have user generated data
6. 1. How I became paranoid 2. Frank Underwood’s greatest compliment 3. Why I respect types 4. How you can be more defensive 5. Takeaways for the sceptics
7. 1 How I became paranoid
11. 10:00 10:02 10:04
12. 10:00 12:00 14:00
16. Tip 1 Don’t dismiss “small” problems
18. Tip 2 Define the absolutes
20. Tip 3 Unit test your defence
21. 2 Frank Underwood’s Greatest Compliment
22. Defensive Programming Tip 4 Be ruthlessly pragmatic
23. 1. That Can’t Happen!
24. 2. How did that happen?
25. 3. How did that ever work?
26. 1. It happened 2. Here’s how 3. I can fix that
27. getsentry.com/welcome/
31. Defensive Programming Tip 5 Monitor & log everything
32. 7% Requests Production Errors
33. 11% Defense Production Errors
34. 36% Ungraphable data Production Errors
35. 46% Type Errors Production Errors
36. 3 Why I respect types
37. W AT!!
40. bit.ly/monitoring-plants
41. Defensive Programming Tip 6 Don’t trust user data
44. Defensive Programming Tip 7 …will be race conditions. There…
45. 4 How you can be more defensive
47. Oh no! That request failed. Try again?
49. Loading…
53. Defensive Programming Tip 8 Don’t forget defensive design
54. 5 Takeaways for the skeptics
56. Tip 9 Make debugging easier
57. Portal
58. A B
59. A B
60. Tip 10 Write defensive code but don’t be defensive
61. bit.ly/defensive-design bit.ly/prag-prog
62. @serverdensity
63. @serverdensity @byrichardpowell Monitor servers & websites Configure Alerts Amazon, Rackspace Google Cloud Custom dashboards