Question

Is it possible to find which method was called on an object without having it in body of the object?

I mean :

 function foo() {
   if(! (this instanceof foo) ) return new foo();
   alert(this.find_which_method_was_called()); // output 'myMethod'
 }

 foo().myMethod();

Answer 1

myMethod() is called after the foo() constructor returns, so there is no chance you could know if it’s called or not in the constructor.

You could, however, wrap your object in a proxy and save the name of all called functions in an array:

function Proxy(object) {

    this.calledFunctions = [];

    for (var name in object) {
        if (typeof object[name] != 'function') {
            continue;
        }
        this[name] = (function (name, fun) {
            return function() {
                this.calledFunctions.push(name);
                return fun.apply(object, arguments);
            };
        }(name, object[name]));
    }
}

Now you can do this:

var f = new Proxy(new foo());
f.myMethod();
alert(f.calledFunctions);