Predictive Prefetching for Angular

Websites are slow! Double-click shows that the average load time on a 3G network is 19 seconds! On top of that, on mobile devices, JavaScript compared to a JPG image with the same size may require x25 more processing time.

How to speed up our apps? Lazy-loading is here to help! By only loading the minimum amount of JavaScript during the initial page load we can improve the UX dramatically. However, this brings another set of questions - how to decide what to load lazily, how to provide instant page load by mindfully prefetching the bundles, without draining the users' mobile data plan?

Machine learning is already playing an essential role in our day-to-day life, and it has the potential to assist in our development process for smaller, smarter, and faster JavaScript applications!

In this talk, we'll see how we can create a machine learning model from a Google Analytics report. Later, by empowering static analysis techniques, we'll map this model to the lazy-loaded JavaScript chunks and apply predictive prefetching and data-driven bundling. In the last part of the presentation, we'll look at Guess.js which provides a sample implementation of these ideas.

Transcript

1. twitter.com/mgechev Predictive Prefetching twitter.com/mgechev github.com/mgechev blog.mgechev.com
2. twitter.com/mgechev
3. twitter.com/mgechev twitter.com/mgechev github.com/mgechev
4. twitter.com/mgechev
5. twitter.com/mgechev comparable to native
6. twitter.com/mgechev Everything comes with a price tag
7. twitter.com/mgechev
8. twitter.com/mgechev
9. twitter.com/mgechev
10. twitter.com/mgechev
11. twitter.com/mgechev
12. twitter.com/mgechev
13. twitter.com/mgechev https://medium.com/dev-channel/the-cost-of-javascript-84009f51e99e
14. twitter.com/mgechev lazy-loading
15. twitter.com/mgechev - Route-based - Component-based Lazy-loading strategies
16. twitter.com/mgechev How do we pick the split points?
17. twitter.com/mgechev often subjectively
18. twitter.com/mgechev sometimes based on data
19. twitter.com/mgechev - Manual - Error-prone but always…
20. twitter.com/mgechev Step 1: Open https://example.com/ Step 2: Determine JavaScript which is likely to be required Step 3: Download the chunks Step 4: Store chunks in browser cache Pre-fetching
21. twitter.com/mgechev How do we pick the priorities of the bundles to pre-fetch?
22. twitter.com/mgechev
23. twitter.com/mgechev Lazy-load everything!
24. twitter.com/mgechev Lazy-load everything! …and let tooling take care of the rest
25. twitter.com/mgechev
26. twitter.com/mgechev /a /a/a /a/b /b /b/a /
27. twitter.com/mgechev /a /a/a /a/b /b /b/a /
28. twitter.com/mgechev /a /a/a /a/b /b /b/a /
29. twitter.com/mgechev /a /a/a /a/b /b /b/a /
30. twitter.com/mgechev
31. twitter.com/mgechev
32. twitter.com/mgechev Route-based splitting
33. twitter.com/mgechev $ npm run build # For Angular CLI $ serve -s dist
34. twitter.com/mgechev Let’s emulate *really* bad conditions
35. twitter.com/mgechev
36. twitter.com/mgechev
37. twitter.com/mgechev Let’s take a look at the GA graph
38. twitter.com/mgechev
39. twitter.com/mgechev
40. twitter.com/mgechev - Main & Settings in same chunk ‣ Update of the source code - Pre-fetch FAQ when the user is at Home Possible optimizations
41. twitter.com/mgechev
42. twitter.com/mgechev early preview
43. twitter.com/mgechev Supports Angular CLI 1.7 Disclaimer
44. twitter.com/mgechev $ npm run eject # For Angular CLI $ vim webpack.config.js
45. twitter.com/mgechev const { GuessPlugin } = require('guess-webpack'); "// ""... plugins: [ "// ""... new GuessPlugin({ GA: 'XXXXXX' }) ] "// ""...
46. twitter.com/mgechev
47. twitter.com/mgechev
48. twitter.com/mgechev How it works…
49. twitter.com/mgechev - guess-ga - guess-parser - guess-webpack Packages
50. twitter.com/mgechev guess-ga Fetching structured data from Google Analytics
51. twitter.com/mgechev const { fetch } = require(‘guess-ga'); fetch({ key: require('./c.json'), viewId: '000000000', period: { startDate, endDate }, routes }) .then(g "=> writeFileSync('data.json', JSON.stringify(g))); guess-ga
52. twitter.com/mgechev guess-parser Gets metadata by statically analyzing our app
53. twitter.com/mgechev guess-webpack Set of webpack plugins which automate the build
54. twitter.com/mgechev GuessPlugin ClusterChunksPlugin RuntimePrefetchPlugin
55. twitter.com/mgechev GuessPlugin ClusterChunksPlugin RuntimePrefetchPlugin
56. twitter.com/mgechev RuntimePrefetchPlugin
57. twitter.com/mgechev /a /a/a /a/b /b /b/a /
58. twitter.com/mgechev Markov Chain / /a /a/:id /b /b/a / 0 0.3 0 0.7 0 /a 0 0 0.9 0.1 0 /a/:id 0 1 0 0 0 /b 0 0 0 0 1 /b/a 0 1 0 0 0 /a /a/a /a/b /b /b/a /
59. twitter.com/mgechev /a /a/a /a/b /b /b/a / Activity: / /a /a/:id /b /b/a / 0 0.3 0 0.7 0 /a 0 0 0.9 0.1 0 /a/:id 0 1 0 0 0 /b 0 0 0 0 1 /b/a 0 1 0 0 0 Probability threshold: 0.5
60. twitter.com/mgechev /a /a/a /a/b /b /b/a / Activity: / /a /a/:id /b /b/a / 0 0.3 0 0.7 0 /a 0 0 0.9 0.1 0 /a/:id 0 1 0 0 0 /b 0 0 0 0 1 /b/a 0 1 0 0 0 Probability threshold: 0.5
61. twitter.com/mgechev /a /a/a /a/b /b /b/a / Activity: / /a /a/:id /b /b/a / 0 0.3 0 0.7 0 /a 0 0 0.9 0.1 0 /a/:id 0 1 0 0 0 /b 0 0 0 0 1 /b/a 0 1 0 0 0 Probability threshold: 0.5
62. twitter.com/mgechev / /a /a/:id /b /b/a / 0 0.3 0 0.7 0 /a 0 0 0.9 0.1 0 /a/:id 0 1 0 0 0 /b 0 0 0 0 1 /b/a 0 1 0 0 0 /a /a/a /a/b /b /b/a / Activity: - Download b.bundle.js Probability threshold: 0.5
63. twitter.com/mgechev /a /a/a /a/b /b /b/a / Activity: - Download b.bundle.js / /a /a/:id /b /b/a / 0 0.3 0 0.7 0 /a 0 0 0.9 0.1 0 /a/:id 0 1 0 0 0 /b 0 0 0 0 1 /b/a 0 1 0 0 0 Probability threshold: 0.5
64. twitter.com/mgechev /a /a/a /a/b /b /b/a / Activity: - Download b.bundle.js / /a /a/:id /b /b/a / 0 0.3 0 0.7 0 /a 0 0 0.9 0.1 0 /a/:id 0 1 0 0 0 /b 0 0 0 0 1 /b/a 0 1 0 0 0 Probability threshold: 0.5
65. twitter.com/mgechev /a /a/a /a/b /b /b/a / / /a /a/:id /b /b/a / 0 0.3 0 0.7 0 /a 0 0 0.9 0.1 0 /a/:id 0 1 0 0 0 /b 0 0 0 0 1 /b/a 0 1 0 0 0 Activity: - Download b.bundle.js - No action Probability threshold: 0.5
66. twitter.com/mgechev /a /a/a /a/b /b /b/a / / /a /a/:id /b /b/a / 0 0.3 0 0.7 0 /a 0 0 0.9 0.1 0 /a/:id 0 1 0 0 0 /b 0 0 0 0 1 /b/a 0 1 0 0 0 Activity: - Download b.bundle.js - No action Probability threshold: 0.5
67. twitter.com/mgechev /a /a/a /a/b /b /b/a / / /a /a/:id /b /b/a / 0 0.3 0 0.7 0 /a 0 0 0.9 0.1 0 /a/:id 0 1 0 0 0 /b 0 0 0 0 1 /b/a 0 1 0 0 0 Activity: - Download b.bundle.js - No action Probability threshold: 0.5
68. twitter.com/mgechev /a /a/a /a/b /b /b/a / / /a /a/:id /b /b/a / 0 0.3 0 0.7 0 /a 0 0 0.9 0.1 0 /a/:id 0 1 0 0 0 /b 0 0 0 0 1 /b/a 0 1 0 0 0 Activity: - Download b.bundle.js - No action - Download a.bundle.js Probability threshold: 0.5
69. twitter.com/mgechev - Personalized bundling - Smarter clustering - Personalize pre-fetching - Reduced chunk over fetching - More robust parsers Future plans
70. twitter.com/mgechev - https://mgv.io/dd-bundling - https://mgv.io/cost-of-js - https://mgv.io/predictive-fetching - https://mgv.io/guess References
71. twitter.com/mgechev A new wave of data-driven web tooling is up to come
72. Thank you! twitter.com/mgechev github.com/mgechev blog.mgechev.com