gistfile1.txt

var F = function() {};
F.prototype.a = 'b';
  
var s = new F();
print(s.a);        
print(s.hasOwnProperty('a'));  //false

s.a = 'c';          // object s will create its new property 'a'
print(s.a);         // c
print(s.hasOwnProperty('a'));  // true;
print(F.prototype.a);     //b;  property in F is not changed