Question

153

Can I override the Javascript Function object to log all function calls?

rated 0 times [ 160] [ 7] / answers: 1 / hits: 28235 / 14 Years ago, mon, march 7, 2011, 12:00:00

Can I override the behavior of the Function object so that I can inject behavior prior t every function call, and then carry on as normal? Specifically, (though the general idea is intriguing in itself) can I log to the console every function call without having to insert console.log statements everywhere? And then the normal behavior goes on?

I do recognize that this will likely have significant performance problems; I have no intention of having this run typically, even in my development environment. But if it works it seems an elegant solution to get a 1000 meter view on the running code. And I suspect that the answer will show me something deeper about javascript.

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myakylas

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answered 14 Years ago morganm · Accepted Answer

The obvious answer is something like the following:

var origCall = Function.prototype.call;

Function.prototype.call = function (thisArg) {

    console.log(calling a function);



    var args = Array.prototype.slice.call(arguments, 1);

    origCall.apply(thisArg, args);

};

But this actually immediately enters an infinite loop, because the very act of calling console.log executes a function call, which calls console.log, which executes a function call, which calls console.log, which...

Point being, I'm not sure this is possible.