Are there several performance penalties for using Objects with functions and mixins, rather than prototypes? [closed]

Answer 1

If you're worried about this you could mix in on the prototype but as Bergi says; when calling a method many times it actually has a shorter look up if you have the method on the instance instead of on it's prototype.

Here is how to mixin on the prototype:

function mixin(source, target){
  for(thing in source){
    if(source.hasOwnProperty(thing)){
      target[thing]=source[thing];
    }
  }
};
var canSpeak = function(){
  //initialize instance specific values
  this.canSpeakMessage="Hello World";
  this.someArrayThatNeedsToBeInitialized=[];
};
canSpeak.prototype.speak = function(){
  console.log(this.canSpeakMessage);
}
var Test= function(){
  //init instance specific values for canSpeak
  canSpeak.apply(this,arguments);
};
mixin(canSpeak.prototype,Test.prototype);


var t = new Test();
t.speak();//=Hello World

Answer 2

If you do OOP using constructors, prototypes, news, etc, this is something V8 (JS engine in Chrome and Node.js) specially optimizes for. Your user properties will be even stored side by side with their internal properties, like in C++ or Java objects.

One of the benchmarks used to tune V8 is heavily object oriented like this http://octane-benchmark.googlecode.com/svn/latest/deltablue.js

If you attach properties dynamically or do some other sleazy tricks, you will of course confuse the heuristics for this and probably set yourself back.

This is of course engine specific.

I should also mention the general disclaimer that if you are doing UI code like "click handler shows an text area", then this doesn't matter. You could be collecting stack traces on every method call and not notice any perf issue.