constructors.js

// a function is just a function.  By default it has no 'this' and returns nothing
function myFunction() {
  this.value = 5;
}

// if I call it, I get nothing back
var obj1 = myFunction();  // obj1 is undefined

// if I call it with 'new', a new empty object is assigned to 'this' and returned to me afterwards
var obj2 = new myFunction();  // obj2 is { value: 5 }