Difference between Phoenix globals and MDN globals

[Gladear]

Environment

• Elixir version (please paste the output of elixir -v):

N/A

• Phoenix and LiveView versions (mix deps | grep -w 'phoenix\|phoenix_live_view'):

4889426ca118fee49b321f5979eea64179410fa9

• Operating system:

• Windows
• MacOS
• Linux
• Other (please specify):

• Browsers (including version) you attempted to reproduce this bug on (the more the merrier):

Actual behavior

Global attributes include values that are not part of the HTML specification (well, not on the MDN anyway), and lacks some others.

Here's the full list, based on a comparison between MDN and this list:

Exist in Phoenix globals, but not in spec:

• alt
• contextmenu
• height
• placeholder
• rel
• target
• type
• width

Exist in spec, but not in Phoenix

• anchor
• autocorrect
• inert
• virtualkeyboardpolicy
• writingsuggestions

Expected behavior

I expect both lists to be in sync (best effort, obviously 😄). We noticed that because people started using some of these attributes on components where it should not exist, which caused issues.

[SteffenDE]

Yeah, I agree. If you want to send a PR please do so. We only need to be careful about the ones that would be removed. If they were valid in the past we should keep them, so maybe we just add?

[Gladear]

After a quick test, it appears that all unknown attributes are assigned to the :global attribute regardless of if they exist in the list of not:

iex> Mix.install([:phoenix_live_view])
iex> defmodule MyComponents do
      use Phoenix.Component
      attr :rest, :global
      def button(assigns) do
        dbg assigns.rest
        ~H"<button {@rest}>Button</button>"
      end
    end
iex> import Phoenix.Component
iex> import Phoenix.LiveViewTest
iex> assigns = %{}
iex> Phoenix.LiveViewTest.rendered_to_string(~H|<MyComponents.button alt="notglobal" unknown_attr="still_rendered" />|)
[iex:7: MyComponents.button/1]
assigns.rest #=> %{alt: "notglobal", unknown_attr: "still_rendered"}

"<button alt=\"notglobal\" unknown_attr=\"still_rendered\">Button</button>"

So, as far as I see, removing attributes would just add a warning about their usage. This warning is both easy to fix, and could catch some bugs in some cases, so I think it would be acceptable? What do you think about that, @SteffenDE ?

I'll open a PR once this is settled 😄

[Gladear]

I opened a PR that does both, but I can easily remove the "removal" part if necessary 😊