I actually found the Javascript 'this' keyword more understandable after working with Python.
>>> class foo():
... def test(this, x):
... print this, x
...
>>> x = foo()
>>> x
<__main__.foo instance at 0xb71928ac>
>>> x.test(1)
<__main__.foo instance at 0xb71928ac> 1
>>> y = foo.test
>>> y(1)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unbound method test() must be called with foo instance as first argument (got int instance instead)
>>> y(x,1)
<__main__.foo instance at 0xb71928ac> 1
In Python, the reference to the current object is an explicitly declared parameter in the method definition, but the parameter is passed implicitly - the value of "this" is whatever is comes before the period when the method is called. If you call it in any other manner, it throws an unbound method error. Javascript is the same way, but instead of throwing an error it will instead pass 'window' implicitly. The equivalent code in Javascript:
function foo() { }
foo.prototype.test = function(x) {
console.log(this, x);
}
var x = new foo();
x.test(1); // prints VM1061:4 foo {test: function} 1
var y = x.test;
y(1); // prints VM1061:4 Window {top: Window, window: Window, …} 1
