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by gear54rus 950 days ago
Do you want to have this in Tampermonkey script ONLY or not necessarily? You can use ResourceOverride addon to simply replace the 100k script with your own script that is almost the same but also assigns the function you need to window.myFn or something. There it can just be picked up by TM.
1 comments
thrdbndndn 950 days ago
Thanks for the suggestion, but the goal is to just use this function in my own code (which has lots of other things going on).

I guess it technically can be done by modifying the existing JS in-place, but doing so with a very large, minified JS would be a nightmare in term of maintenance.

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danShumway 949 days ago
To parent off of GP, I've run into this recently while working on some webextension code and I'm thinking my solution is going to be to monkey-patch the script, but merely to expose a reference to the object/function in question.

So TLDR don't monkey-patch a giant minified source file with a bunch of your own code. Monkey-patch the function just enough to get it to be exposed globally with its context, and then have your code separately reference it.

This is still fragile (unless you have a stable entry point with regex or something, which is not completely certain to exist, it'll likely break whenever the script changes), and is still not ideal, and I'm still thinking a bit to see if I can do anything better, but I suspect it's more stable than trying to access the function directly by coding the path and should be a great deal simpler as well since it will work even if the function/context is in a closure.

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Of course, you might be lucky and there might actually be a way to get at the function. For example, I am separately looking into seeing if I can figure out a clean way to reliably look for imports exposed through a webpack bundle, since those are exposed globally and if you can find the paths reliably you should be able to get access to any of the imports (although you still won't have access to the closures). I haven't made much progress on it though, mostly because it's kind of frustrating to work on.

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There is also the possibility (although I suspect it would get very messy very quickly, and I'm not sure of current browser support) that you could theoretically maybe rig something together with `function.caller` (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...), possibly patching the minified source file merely to remove "use strict".

I have not messed with `caller` in probably close to a decade at this point, so I make no promises at to whether it still works at all :) but... in its heyday before we realized how wildly insecure it was, it did allow reconstructing the stack from a function in-code in some situations.

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