Refactor instances of JQuery, using ES6 and latest javascripts updates

[christinach]

What maintenance needs to be done?

Refactor all files that have instances of JQuery and use ES6 and any further additions/improvements in Javascript until now.

Level of urgency

• High
• Moderate
• Low

Why is this maintenance needed?

• Drop JQuery as a dependency.
• We can use newer web standards and browser apis without the need of loading JQuery library. For example use Fetch instead of .ajax.

Acceptance criteria

• All JS files are refactored and don't use JQuery but ES6 JS improvements.
• Replace libraries that use JQuery (for example data-tables).
• Add documentation about this changes.

References

• removing-jquery-from-github-frontend
• how-to-remove-jquery-from-javascript

@christinach will break this ticket into smaller tickets.