var fun = function() {
  console.log(this);
};

console.log(this);
fun();
/*
  [Binding Pattern]
    1. Global Reference
    2. Free Function Invocation
  [Binding Target]
    : The global object(which is window in a browser)
  [What's it for?]
    : Not useful, but something had to be chosen as a binding for "this" in these cases
*/

fun.call(obj);
fun.apply(obj);
/*
  [Binding Pattern]
    3. .call or .apply Invocation
  [Binding Target]
    : The first argument of .call or .apply
  [What's it for?]
    : To manually specify a 'this' binding, like real arguments
*/

new fun();
/*
  [Binding Pattern]
    4. Construction Mode
  [Binding Target]
    : A new object created for that invocation
  [What's it for?]
    : In order for constructors to operate on the instance they're creating
*/

var obj = {
  method: fun
};
obj.method();
/*
  [Binding Pattern]
    5. Method Invocation
  [Binding Target]
    : Object on the left of the "call time" dot
  [What's it for?]
    : In order for methods to run in the context of an object they're in
*/