Confusions with this variable's context which arise with constructor invocation pattern for regular and arrow function

confused-this.js

 function GetValue1(){
  this.value = 10;
   // using regular funciton to access the varialbe `this.value`
  var printValue = function(){
    // Since printValue is an independent funciton and not a property of the GetValue1 constructor, 
    // so when this is called as constructor, printValue points to globalScopr
    // where in case of reguar funciton call, this will bound to the execution context of GetValue1
    console.log('The value of this.value is, ', this.value) //consoles 20
  } 
  printValue()
}

function GetValue2(){
  this.value = 10;
  // using arrow function to access `this.value`
  var printValue = () => {
    // Arrow function in any case will have context of its enclosing block
    console.log('The value of this.value is, ', this.value)
  } 
  printValue()
}
var value = 20
//acessing GetValue1 as a constructor
var x = new GetValue1() 
//calling GetValue1 as a regular function
GetValue1()
// accessing GetValue2 as a constructor
new GetValue2()
console.log(x)

confused-this2.js

function foo(){
  console.log("foo.a =", foo.a)
  console.log("this.a =", this.a)
}

var foo1 = () => {
  console.log("foo1.b =", foo1.b)
  console.log("this.b =", this.b)
}
foo.a = 20
var a = 10
foo()
//foo.a =20
//this.a =10
new foo()
//foo.a =20
//this.a =undefined

foo1.b = 30
var b = 40
foo1()
// foo1.b =30
// this.b =40
new foo1()
// error: Uncaught TypeError: foo1 is not a constructor