What is the rationale for the behavior of the 'this' keyword in JavaScript?

Question

I am asking this from a language design point of view. So I am trying to find out

1. What is the rationale for the behavior of this?
2. To what

Answer 1

I think unbound "this" is a mistake. Otherwise it is quite handy. Unbound "this" opens the possibility of misinterpreting the context most prominently apparent in event handling of browsers. Also javascript libraries have different opinions of what "this" should refer to in event handling and many callback constructs (like map, filter).

Removing unbound "this" probably wouldn't make things any more difficult.

Edit: I guess an alternative syntax example will make my stance clearer.

function Foo()
{
    //both this refer to the Foo instance
    this.blah=this.function(){this.bar;};

    //second this refers to baz
    this.blah=baz.function(){this.bar;};

    //second this refers to anonymous function itself
    this.blah=function(){this.bar;};
}