JavaScript function type checking and overloading

fn.js

function create() {
  var types = Array.prototype.slice.call(arguments, 0, arguments.length - 1);
  var body = arguments[arguments.length - 1];
  return function () {
    if (arguments.length < types.length)
      throw new Error("Argument count mismatch.");
    for (var i = 0; i < types.length; i++) {
      if (arguments[i].constructor != types[i] && !(arguments[i] instanceof types[i]))
        throw new Error("Argument type mismatch. (" + types[i].name + ")");
    }
    return body.apply(this, arguments);
  }
}

function overload(a) {
  if (arguments.length == 1) return a;
  var c = overload.apply(this, Array.prototype.slice.call(arguments, 1));
  return function () {
    try {
      return a.apply(this, arguments);
    } catch (e) {
      return c.apply(this, arguments);
    }
  }
}

var f_string = create(String, function(s) {
  console.log("String: " + s);
});

var f_number = create(Number, function(n) {
  console.log("Number: " + n);
});

var f_bool_string = create(Boolean, String, function(b, s) {
  console.log("Boolean: " + b + ", String: " + s);
});

var f = overload(f_string, f_number, f_bool_string);

f(2.1); // logs "Number: 2.1"
f(true, "Testing"); // logs "Boolean: true, String: Testing"
f("Test"); // logs "String: Test"
f(true); // throws Error;