Count the javascript functions on a page (with javascript)

Question

Good day all. I would like to count the js functions present on a given page, and then send this number via ajax (the ajax part is the simple part) do you think is it possible to achieve that in javascript? what should be the best way to do it? thanks in advance.

explanation: I'm trying to figure out how to counter measure some fraud attempts on some subscription pages, I suspect that some javascript is injected on the page before the user click, so having the number of functions present at the load event, and then the number of those present on the submit event, should lead me in the right direction.

Do you understand that you can do fraud even without adding new functions, and whatever code you write, it doesn't execute again after it is loaded onto the browser? — Praveen Kumar Purushothaman, Dec 11 '15 at 11:18
sure, this is only one of the researches I'm doing to this front. what I would like to do is a function that counts functions, so I can fire it whenever I need. — Matteo Bononi 'peorthyr', Dec 11 '15 at 11:19
Maybe it would be better to make a checksum over the whole DOM — brandelizer, Dec 11 '15 at 11:19
@freedomn-m You know what I am trying to say, but still you ask! — Praveen Kumar Purushothaman, Dec 11 '15 at 11:19
@brandelizer I don't think that would either be possible, coz due to the dynamic nature, new code may be injected, or removed, say for eg., animations, user activity? — Praveen Kumar Purushothaman, Dec 11 '15 at 11:20
I'm thinking about counting all the word "function" into the page... but this will not count the external files. — Matteo Bononi 'peorthyr', Dec 11 '15 at 11:28
Possible solutions here : http://stackoverflow.com/questions/11279441/return-all-of-the-functions-that-are-defined-in-a-javascript-file — Tᴀʀᴇǫ Mᴀʜᴍᴏᴏᴅ, Dec 11 '15 at 11:29
You executing js doesn't have access to the source file it's executing from — freedomn-m, Dec 11 '15 at 11:29

score 2 · Answer 1 · edited Dec 11 '15 at 11:25

2

Well, if someone is injecting code to your site, they could just as easily use that code to turn off your code counting functions. You can never trust anything that happens on the client side and must validate everything on the server.

As for the technical side, you'd use a tool like acorn to traverse the syntax tree and find all FunctionDeclaration and FunctionExpressions (and arrows, concise method definitions and methods). That would not find all functions, but it would find all statically created ones.

Once the code started executing it's impossible since it's easily reducable to the halting problem. You don't know if a code will create a function at some point in the future.

edited Dec 11 '15 at 11:25

Praveen Kumar Purushothaman

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answered Dec 11 '15 at 11:22

Benjamin Gruenbaum

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yes, indeed they "could" turn off my CM, but I'me actually researching this, so I'm only interested in view some numbers, in this case, the number of functions at the page load, and the number of functions at the submit of the form. – Matteo Bononi 'peorthyr' Dec 11 '15 at 11:30
Then no, there is no "global counter of created functions", you can _try_ overriding `Function` itself with a subclass but I don't think that'd work in most environments. – Benjamin Gruenbaum Dec 11 '15 at 11:31
understand.. the overriding options doesn't seems the way atm. – Matteo Bononi 'peorthyr' Dec 11 '15 at 11:32

Count the javascript functions on a page (with javascript)

1 Answers1