Proposal: `scripting.executeScript` without specifying `tabId`

[carlosjeurissen]

Background

1. currently scripting.executeScript / tabs.executeScript require one to define the tabId of the main_frame or sub_frame to inject the content script in.
2. extension popups have their tabId set to -1 (no tabId). This makes sense as they are no tabs, but puts limitations like the inability to use executeScript for iframes within extension popups.

Proposal

Allow to only specify a frameId as target when running scripting.executeScript / tabs.executeScript. This basically means either tabId or frameId will be required when running executeScript or insertCSS.

Reasoning

This will allow dynamic contentscript to be injected into frames within non-tab environments like extension popups, and to allow injection of script when it's faster / more convenient to not specify a tabId.

Requirement

All frameIds should be unique for this to be implemented. See:

• Proposal: unique frameIds across windows and tabs  #90

[carlosjeurissen]

As discussed during the 2021-11-11 meeting, this can be tricky as of right now frameId is not unique in all contexts. A potential alternative proposal was to use a window object.

You can think about a syntax like this:

browserOrChrome.scripting.executeScript(
    {
      target: {window: someFrame.contentWindow},
      files: ['script.js'],
    },
    () => { ... });

[carlosjeurissen]

As with #12 (comment)

With the introduction of documentId this seems to become possible.

[erosman]

See also:
Proposal: Default to Active Tab in scripting.executeScript()

[rdcronin]

We discussed this at the WECG meet-up.

We're agreed that this is useful functionality. There's one tricky bit, which is that currently, the main frame is always 0 (whereas subframes are globally-unique). While we've talked about changing that, it's a very breaking change and not something we're actively looking at.

We tentatively agred that we're supportive of:

• Allowing non-zero frameId without a tabId (new)
• Allowing any documentId without a tabId (new)
• Allowing any frameId with a tabId (as today)

This would also allow extensions to inject in non-tab contexts, as @carlosjeurissen mentioned in the issue report.

We also pointed out that this does introduce a requirement that non-main-frame IDs are globally unique. This is already an attribute in most Chromium-based browsers, Firefox, and Safari, but is now a requirement for this functionality.

[Rob--W]

Filed https://bugzilla.mozilla.org/show_bug.cgi?id=1891480 to track this at the Firefox side.