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Is using a self defined constructor function more expensive than an object literal? 

var obj = function(){
    this.foo = "bar; 
};

The reason why I ask is because, if I declare an object literal as such: 

var obj = { foo: bar };

I wonder, if behind the scenes it does the same as: 

var obj = new Object(); 
obj["foo"] = "bar";

If that's the case, I'd assume that they're both approximately as expensive, and choosing one over the other would be trivial (for a case like this).

html_programmer
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    Worrying about these performance differences is futile. `new Object` is never used. – elclanrs Aug 04 '15 at 19:07
  • @elclanrs Ok cool... it's sometimes the little things I wonder about the most. – html_programmer Aug 04 '15 at 19:08
  • None of your examples *declares* a constructor function, and `Object` is certainly not self-defined. – Bergi Aug 04 '15 at 19:27
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    `new Object` is much more expensive, as it needs to resolve the `Object` identifier and call a function (you might have overwritten it!). The object literal in contrast is statically optimisable. And, of course, it's much easier to read. And a shorter string of code to transfer and compile. – Bergi Aug 04 '15 at 19:30
  • There's always jsperf, and I believe this is a dupe, so there's probably something there already. – Dave Newton Aug 04 '15 at 19:31
  • Woops indeed, missed that somehow. – html_programmer Aug 04 '15 at 19:39
  • Um, an `obj` function is very different from an `obj` object. Use what you need, not what is more expensive. – Bergi Aug 04 '15 at 19:53

0 Answers0