How to know if a function is called from the javascript console?

No matter how much you obfuscate and hide your code, any javascript that can be executed on the client side can be executed in the console and you should always be running permissions/security checks on the server side if you wish to have any real control over the security of such functions.

That being said, you can restructure your code inside an immediately invoked function expression which will not be callable as easily from the console as usual like so:

(function() {
    var myUncallableFunction = function() { alert('meow'); }
})();

the function myUncallableFunction will only be able to be called from within the parent function as it is a local variable to that parent function and is therefore inaccessible outside of it.

You will still be able to call this function inside of that parent however like so:

(function() {
    var myUncallableFunction = function() { alert('meow'); }
    myUncallableFunction();
})();