For Array, is it more efficient to use map() & reduce() instead of forEach() in javascript?

Question

1)As we know, there\'s no side-effect with map() and reduce(). Nowadays, we also have muti-core on cell phone. So is it more efficient to use them?

2)On the other h

Answer 1

I just tested this today, using map and reduce over floating point numbers, with the latest node.js version, and the answer is that map and reduce was two orders of magnitude slower than an regular for loop.

var r = array.map(x => x*x).reduce( (total,num) => total+num,0);

~11,000ms

var r = 0.0;
array.forEach( (x,i,a) => r += x*x  )

~300ms

var r = 0.0;
for (var j = 0; j < array.length;j++){
    var x = array[j];
    r += x*x;
}

~35ms

EDIT: One should note that this difference is much less in Firefox, and may be much less in future version of Node / Chrome as well.