Explanation of This in Javascript

gistfile1.js

This is set when function is called

This also depends on HOW it is called. Not how it is defined. 

Examples = 

constructor => this = new object ({})
var test = new Test();

method => this = receiver (test)
test.something()

function => this = window
var myFunc = clock.run;
myFunc()

call/apply => this = first arg (obj)
myFunc.call(obj)
myFunc.apply(obj)

To solve the problem of wrong "this"
Use:
  var that = this;
  Funct(function () {that.funct2();}, x)
  
Or using Bind

  var func = this.func2.bind(this);
  setFunct(func, x);