feature: add support for multiple elements highlight

[IArny]

I would propose feature to support multiple elements highlight. All elements selected with attachTo.element will be highlighted if attachTo.multiple is true. I added multiple flag to attachTo field to keep old behavior. I'd appreciate your feedback for this PR.

Also this PR can resolve #525 issue

[Krumil]

This will be a life-saver for me! Thanks

[RobbieTheWagner]

@IArny would you be able to rebase and fix conflicts please? Thanks!

[RobbieTheWagner]

@IArny I'm so sorry, but it looks like we have conflicts again. Could you rebase one more time please?

[IArny]

@rwwagner90 I've fixed conflicts and tests, could you check it agait, please

[IArny]

@rwwagner90 Could you review my PR, please

[IArny]

Hey, is anyone here? Would appreciate this to be merged to master @rwwagner90

[RobbieTheWagner]

@IArny apologies, I have not had a chance to review this yet.

[RobbieTheWagner]

@IArny I finally got a chance to take a look at this. I think it might make more sense to have attachTo be an array of objects with {element, on} like it currently is, just would accept an array instead of just a single element. If we wanted to keep the old API as well, we could use something like isArray to check if the option passed is an array, etc. What do you think?

[IArny]

@RobbieTheWagner thanks for review, I think that attachTo as an array would be useful feature, but we can leave current implementation as an option too. Maybe you can merge current PR and I will make attachTo as an array in next PR? A bit difficult to support this PR as it contains some linting updates.

[RobbieTheWagner]

@IArny I don't think we should merge this PR, unfortunately. I think basically we should do:

if(Array.isArray(attachTo) {
  // loop through the attachTo options and do all the attachTo things
} else {
// Just do what we already do when it's a single element
}

I do not like that your implementation requires a root element selector and selects all elements under it when you pass multiple. I would rather be explicit about all the elements you want highlighted.

[juanitoddd]

This will be much a nice feature !
I guess the Array approach enables the option to place the Pop-up relative to an element but also hightlight another one:

attachTo: [ {element: '.main-highlight', on: 'left'}, {element: '.secondary-highlight'}, ]

[500Foods]

So it looks like this is almost ready for release? Is that the case?

[davidperezvw]

Are we gonna see this change on release any soon?

[500Foods]

Lots of repo activity! Is this in the works now?

[RobbieTheWagner]

@IArny I don't think we should merge this PR, unfortunately. I think basically we should do:

if(Array.isArray(attachTo) {
  // loop through the attachTo options and do all the attachTo things
} else {
// Just do what we already do when it's a single element
}

I do not like that your implementation requires a root element selector and selects all elements under it when you pass multiple. I would rather be explicit about all the elements you want highlighted.

This was the last place we left off. This is not planned currently, but if someone wanted to spike it out, we would definitely accept PRs!

[RobbieTheWagner]

Highlighting multiple things was implemented in #2995