Can I intercept a function called directly?

Question

In this code I created a function called someFunction. Then I modified Function.prototype.apply and call methods. So instead of my function code is working I am running my interception code (which shows an alert). But neither "call" nor "apply" intercepts direct method call. Is it possiple to intercept this?

Function.prototype.call = function(){alert("call");};
Function.prototype.apply = function(){alert("apply");};
function someFunction(){}
window.onload = function(){
    someFunction.call(this); //call alert is shown
    someFunction.apply(this); //apply alert is shown
    someFunction(); //how can I intercept this?
}

Answer 1

You can only override a known function by setting another function in its place (e.g., you can't intercept ALL function calls):

(function () {
    // An anonymous function wrapper helps you keep oldSomeFunction private
    var oldSomeFunction = someFunction;

    someFunction = function () {
        alert("intercepted!");
        oldSomeFunction();
    }
})();

Answer 2

You could iterate over the global scope and replace any objects of function type you find which aren't "yours".

Answer 3

Function.prototype.callWithIntercept = function () {
  alert ("intercept");
  return this.apply (null, arguments);
};

---

var num = parseInt.callWithIntercept ("100px", 10);