Echo JS 0.11.0

Only optimize cases like this if the performance is actually effecting your application.  While it's interesting and nice to be aware of, the underlying engines can and do change over time.

Good idea. You will find this message in the conclusion of the post too.

Could be interesting to compare it to `array.concat([item])`. 

I know that Array.prototype.push is generic and can work with several kinds of objects but not sure about `concat`.

I made a perf test that includes concat too: https://jsperf.com/spread-operator-head-vs-tail/13.
Seems like [item].concat(array) is the fastest.

Nice! I'm glad I brought that up!