Variable naming conflict causes script to fail to run

Hello there! I've been trying to use a specific script called "Twitter Media Downloader" with the Userscripts app on both iOS and macOS - unfortunately, there appears to be a problem, which only occurs on the Userscripts app, but not on other userscript managers, namely Tampermonkey.

Twitter Media Downloader userscript: what it does

The "Twitter Media Downloader" userscript does a few things:

1. add a SVG "download" logo to Tweets containing a photo or video

2. then once clicked, the userscript will use the GM_download() function to download the file to the user's computer, using a filename template stored with the key filename using gm_set/getValue.

3. If the download was successful, it'll save the Tweet's Status ID (e.g 1509343022340837377) in localStorage under the key history, and the SVG logo will be changed to "completed".

The problem

Other browsers

The userscript works well under Tampermonkey, both running under Firefox 98 and Chrome Mobile (Kiwi Browser) 99 (albeit the script needed a few modifications because of CSP not working in mobile.twitter.com).

In Userscripts by Quoid

However, running it under the Userscripts app under Safari on iPadOS 15.4 and and macOS Safari 15.3 fails to work; the "download" button is not shown on Tweets with images.

*Same Tweet in Safari; doesn't show the download button. On the Mac, but the result appears to be same on the iPad.*

CSP problems

In the Console, it indicates that both injections (due to CSP) failed because of the error "Refused to execute a script because its hash, its nonce, or 'unsafe-inline' does not appear in the script-src directive of the Content Security Policy.
content.js:194"

SyntaxError on fallback injection

Interestingly, on the fallback (second) injection, the script throws a strange error: SyntaxError: Cannot declare a const variable twice: 'filename. The SyntaxError only appears to occur on the "Twitter Media Downloader" userscript and not the TestScript provided in the issuetemplate.

inject-into resolves CSP, but script still does not work

So, I searched around here for solutions, and setting // @inject-into content in the script's metadata seems to the script to be injected with no error and no double-injection caused by CSP.

Still, even with inject-into set to "content", the script fails to take effect: the Download button does not appear on Tweets with Images.

Despite these issues, I love and use this extension on my iOS devices. Having userscripts on my iOS devices is something that I could only have dreamed of as little as a few years ago, and this app has been amazing for optimizing and customizing my Web experience - even in the locked-down ecosystem of the iPhone.

Twitter Media Downloader modified.js.txt

System Information:

macOS or iOS version: 12.2.1
Userscripts version: 4.1.0
Safari version: 15.3
Is this issue related to script injection? It appears to be
Did the test script (pasted above) successfully run on your machine? Yes. CSP bypass causes two injections (and two console responses by the test script), but works otherwise.

Update: it appears as if the script does not execute at all; I made an error while attempting to modify the script. In Firefox with Tampermonkey, it throws an error in the Console due to my error, while in Safari with Userscripts, the script does not run at all, as evidenced by the lack of an error.

Adding a console.log message to the script also indicates that the script, in fact, does not run at all within Safari with Userscripts - there is no console entry in Safari, while FIrefox with Tampermonkey does display the console entry. You can confirm this with the modified script I've attached; it should display a dialog box and console.log message in Tampermonkey, but won't in Userscripts, indicating that the script doesn't execute at all.
Twitter Media Downloader modified 2.txt

[quoid]

@jonathan2384

// @grant       GM_registerMenuCommand
// @grant       GM_setValue
// @grant       GM_getValue
// @grant       GM_download

None of those APIs are supported. Check out the docs.

There's already open issues to add support for them, but it could be some time before they are supported.

Further, this also exposed a conflict in the content script that I am going to correct, so thank you.

[quoid]

@jonathan2384

indicates that the script, in fact, does not run at all within Safari

Check the console for errors. There should be an error like the one below. The injected code and the userscript are both trying to use the same named const which causes an error and makes the userscript fail to run - this is the conflict I mention above.

Edit: I missed that you mentioned this already ^^ this should be why you can't run the script. I am going to be fixing the filename issue in the next beta build, but I won't be adding support for those missing API methods for sometime.

[quoid]

@jonathan2384

I played with that userscript a bit to get it to function. I am not sure if it is totally functioning as intended, but it allows me to download images from twitter, but I had to do a bit a work. Here's what I did:

• Line 109 had no error check for undefined - so if an tweets image media was not returned the download would fail.
• Line 284 was using GM_download which I think is Tampermonkey specific. I changed it to the more universal GM.xmlHttpRequest.
• I was unsure how downloads were actually meant to start after clicking the button the request was successful so I had to add that to the onload callback for GM.xmlHttpRequest
• There seems to be some mechanism for naming the files to be downloaded, but I didn't have time to dig into that logic so that use the current time...
• Changed GM_setValue and GM_getValue to GM.setValue and GM.getValue - even if Userscript support the _ versions the userscript would still fail because the userscript is using the _ versions as if they are async when the _ versions are the non async versions of their . counterparts - if expecting async the author should use GM. not GM_ (and they author is using both async and non async calls to these methods which is confusing)

It's not perfect but here it is:
Userscript.txt

Thank you for taking your valuable time to help me out with getting the userscript working with your extension - I really appreciate it. I'll continue to build upon the script that you generously modified to make the behavior of it more akin to the original - I've gotten the naming working.