use-restrict.txt

"use strict";
var animal = {
  kind: "Cow",
  which: function () {
    console.log(this.kind);
  }
};
var animalFunc = animal.which;
animalFunc(); 


// error kind of undefined, because of use strict.
----------------------------------------------------------

var animal = {
  kind: "Cow",
  which: function () {
    console.log(this.kind);
  }
};
var animalFunc = animal.which;
animalFunc();

// undefined as window object does not contain kind variable