Active 8.x javascript issues

User pain Issue Created
14% details#2119299: Make sure D8 works with mobile proxy browsers 2013-10-24
14% details#2137235: Make core JS work with a subset of jQuery 2013-11-16
11% details#1090592: [meta] Use HTML5 data-drupal-* attributes instead of #ID selectors in Drupal.settings 2011-03-12
11% details#2513356: Add a default CSP and clickjacking defence and minimal API for CSP to core 2015-06-27
11% details#2651660: Investigate where and how a frontend framework could be used 2016-01-17
11% details#2809281: Use ES6 for core JavaScript development 2016-09-30
9% details#2465749: [meta] Widespread HTML validation issue - The ID attribute MUST be unique on the page. 2015-04-05
9% details#2842298: [policy, no patch] Drop IE9 and IE10 support from Drupal 8.4.x 2017-01-10
9% details#2885090: JS Roadmap for 8.4 2017-06-10
7% details#1419652: JavaScript logging and error reporting 2012-01-28
7% details#1440628: [Meta] javascript toolbar/tableheader with url fragment mess 2012-04-03
7% details#1574470: Selectors clean-up 2012-05-12
7% details#1611258: Integrate JS internationalization with third party libraries 2012-05-31
7% details#1644090: [Meta] form data loss 2012-06-18
7% details#1649654: Non-trivial JavaScript files need GPL license declaration for compliant distribution to browsers 2012-06-21
7% details#1824634: [meta] Dropbutton accessibility issues 2012-10-27
7% details#2748269: Evaluate when & how to use jQuery 3 slim version 2016-06-14
6% details#1490312: [META] Improving CSS and JS preprocessing 2012-03-19
6% details#1649670: [META] Improving Drupal sites JavaScript Licence Compliance 2012-07-19
6% details#1770720: [META] Gradual changes to Field UI 2012-09-11
6% details#1842036: [META] Convert all confirm forms already converted to new routing system to use modal dialog 2012-11-16
6% details#1842040: [meta] Decide on where to use modal dialogs 2012-11-20
6% details#2044579: [meta] Supporting single page application development on Drupal Core. 2013-07-18
6% details#2431671: [meta] Add in js- prefixed classes for separation of JS & CSS functionality 2015-02-23
6% details#2655556: [META] Dramatically improve Drupal-provided user interactions through perceived performance boosts and optimistic feedback 2016-01-23
4% details#1787222: [meta] Strategy for updating vendor JS libraries within a major stable version 2012-10-12
4% details#2490140: [Meta] Make sure contrib use ESLint 2015-05-17
3% details#2323895: [Meta] Document format/content of various YML files 2014-08-19
3% details#2818655: Introduce `Support:` syntax tagging Browser Hacks in source code 2016-10-14

Sorting of the JavaScript issue queues based on user pain rating.

User pain = Type * Priority * Public / Max score

Highlighted rows are killer issues , issues that take a significant effort to fix due to their complexity.