[Firefox] Consider to use (programmatic) content scripts API

[kekkc]

Current implementation of tabs.executeScript() causes many problems, e.g. no proper run-at document-start support.

Any plans to use the new, preferred Content scripts API?
https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Content_scripts
https://bugzilla.mozilla.org/show_bug.cgi?id=1332273

[derjanb]

Current implementation of tabs.executeScript() causes many problems, e.g. no proper run-at document-start support.

Tampermonkey doesn't use tabs.executeScript and you can enforce proper document-start support by setting "Inject Mode" to "Instant". Do you know other problems?

Any plans to use the new, preferred Content scripts API?

I'l check that once it's clear that the current @include and @match syntax can be supported.
https://bugzilla.mozilla.org/show_bug.cgi?id=1445909

[kekkc]

Tampermonkey doesn't use tabs.executeScript and you can enforce proper document-start support by setting "Inject Mode" to "Instant". Do you know other problems?

Mostly that the current implementation doesn't work reliably for document-start. E.g. I use the following script:
`// ==UserScript==
// @name No Events
// @author Sacharja
// @Version 1.3.0
// @description Disables annoying events
// @namespace sacharja
// @run-at document-start
// ==/UserScript==

function clearEventPROX(a) {
if (!a) return;
a.opener = cloneInto(null, a);
}
if (unsafeWindow) clearEventPROX(unsafeWindow);`

When I go to https://mathiasbynens.github.io/rel-noopener/ I can click "Click me!!1 (same-origin)", close the opened tab and go back to first one and it's not changed (the script is working via the instant setting). However, if I reload the tab then, click again on "Click me!!1 (same-origin)" & close the opened tab, the original one is changed (message "hacked...").

Whatever workaround is used by TM to inject scripts instantly, it's not guaranteed for 100% that the script will always execute at document-start.

[derjanb]

@kekkc Thanks for that example. It's working reliably at Chrome, but at Firefox Tampermonkey sometimes seems to run after the (inline) page scripts were executed. I'll check that.

[kekkc]

Don't invest too much time, it's a known FF bug and the reason behind Content scripts API ;) Currently there seems to be no other way in FF to reliably run at document-start.
https://bugzilla.mozilla.org/show_bug.cgi?id=1189770
greasemonkey/greasemonkey#1849

[derjanb]

I discovered at least one way: add a break-point to an inline script and the issue will never happen. 🙄

[derjanb]

@kekkc The problem is that Tampermonkey uses a "document_start" content_script which is defined at manifest.json, but I do see the page scripts running before. If this doesn't work, then also any other dynamically defined programmatic content script is not guaranteed to run before the page scripts, right?

[tophf]

I do see the page scripts running before.

Firefox implementation of WebExtensions API still has many bugs in its core parts so it wouldn't surprise me if this is yet another one.

[derjanb]

Sorry. I was in the wrong movie! It's just https://bugzilla.mozilla.org/show_bug.cgi?id=1376932 🙄
I'll use the workaround to make instant injection work reliably at the next beta.

[derjanb]

@kekkc The issue is fixed at 4.6.5741beta

[kekkc]

Pretty cool, thx for the quick fix ;)

[derjanb]

The issue is fixed at 4.6.5741beta