Array rotate //Javascript Function
Rotate the elements of an array with the minimum possible amount of movements.
It's thousands faster than using sequences of "array.unshift(array.pop())" or "array.push(array.shift())" due to memory moving on the "unshift" and "shift" methods. It also doesn't use a helper array, so it's fast and requires no aditional memory.
[UPDATED CODE CAN BE FOUND HERE]
//+ Jonas Raoni Soares Silva //@ http://jsfromhell.com/array/rotate [v1.0] rotate = function(a /*array*/, p /* integer, positive integer rotate to the right, negative to the left... */){ //v1.0 for(var l = a.length, p = (Math.abs(p) >= l && (p %= l), p < 0 && (p += l), p), i, x; p; p = (Math.ceil(l / p) - 1) * p - l + (l = p)) for(i = l; i > p; x = a[--i], a[i] = a[i - p], a[i - p] = x); return a; };
Usage
document.write( "rotate([1,2,3], 2) = ", rotate([1,2,3], 2), "<br />", "rotate([1,2,3], -2) = ", rotate([1,2,3], -2), "<br />", "rotate([1,2,3], 1000) = ", rotate([1,2,3], 1000), "<br />" )
