[GeneralMayhem]

My favorite trick along those lines:

  var cache = SomeClass.prototype.someMethod;
  SomeClass.prototype.someMethod = function () {
    debugger; // or `throw "stacktrace"`
    cache.apply(this, arguments)
  }

Inserts a stack trace right in the middle of executing someone else's code, which is nice for tracking down why/when that function gets called if documentation is poor, without changing functionality.