Course.js: remove jquery and convert to typescript

[BramDevlaminck]

This pull request removes jquery code out of course.js

progress on #3590, closes #3923 .

[lgtm-com]

This pull request introduces 2 alerts when merging f52a4b1 into 7cce90f - view on LGTM.com

new alerts:

• 2 for DOM text reinterpreted as HTML

[lgtm-com]

This pull request introduces 1 alert when merging 957be15 into 7cce90f - view on LGTM.com

new alerts:

• 1 for DOM text reinterpreted as HTML

[bmesuere]

A minor nitpick: I think template strings (between backticks) would look cleaner for the selectors where you now have to escape the double quotes, e.g., in type=\"radio\".

[BramDevlaminck]

A minor nitpick: I think template strings (between backticks) would look cleaner for the selectors where you now have to escape the double quotes, e.g., in type=\"radio\".

I've applied this and also changed the .eslintrc to allow this. With the previous .eslintrc eslint would not allow this since it forced you to use double quotes on every string