Bracket access is significantly slower than property access

[Ryosuke Niwa]

Created attachment 233135 [details]
Microbenchmark

function getByVal(object, property) {
    return object[property];
}

function getById(object) {
    return object.myProperty;
}

The first function appears to be ~3.5x slower than the second function even if getByVal is always called as getByVal(object, 'myProperty').

It's only 1.5x slower on Chrome 35 and 2.2x slower on Firefox 30.

[Ryosuke Niwa]

Note that it's 3.7x slower in the shipping Safari so it has gotten better.

[Ryosuke Niwa]

(In reply to comment #1)
> Note that it's 3.7x slower in the shipping Safari so it has gotten better.

4.7x*