gistfile1.js

var T = function(){ this.t = function(){return 't'} }; 
T.prototype.tp = function(){return 'tp'};

var inst = new T(); 

console.log(inst.hasOwnProperty('t'), inst.hasOwnProperty('tp'))
console.log(inst.t(), inst.tp())
>> true false
>> t tp

console.log(T.prototype.t, T.prototype.tp)
>> undefined function (){return 'tp'}