[perf] Reading object properties vs Reading array fields

[Ezelia]

Hello all,

 

Just wanted to share with you a little test I made, don't know if it's representative ...

 

I allways thought that reading array fields was faster than reading object properties  (maybe because of "for(;;)" is faster than "for in" syntax) .
but I made a simple test with jsperf that gave me the opposite result : http://jsperf.com/object-prop-vs-array

 

can you confirm that with real life examples ?

 

 

 

[mgutz]

Whoa! I would have thought they would be the same, a['foo'] === a.foo

 

I discovered issues with JsPerf in the past though when I was testing callbacks vs promises but that was async code.

[Ezelia]

@mgutz actually it's not what's I'm saying here    a['foo'] is the exact equivalent of a.foo  I don't think you'll get any performance gaine here.
what I did in the example is comparing array of values for example [30, 30, 40, 22] to an object holding each value in a property, example {x:30, y:30, z:40, p:22}