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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())".
Created: 2006.01.02 - Modified 2006.04.23

//+ Jonas Raoni Soares Silva
//@ http://jsfromhell.com/array/rotate [rev. #2]

rotate = function(a, p){
    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;
};

<script type="text/javascript">
//<![CDATA[

document.write(
    "rotate([1,2,3], 2) = ".bold(), rotate([1,2,3], 2), "<br />",
    "rotate([1,2,3], -2) = ".bold(), rotate([1,2,3], -2), "<br />",
    "rotate([1,2,3], 1000) = ".bold(), rotate([1,2,3], 1000), "<br />"
)

//]]>
</script>

rotate(vector: Array, rotateBy: Integer): Array

Rotates the array elements to the left or right and, returns the own array.

vector

array to be rotated

rotateBy

specifies how many positions the array should be rotated by, negative values rotate to the left and positive ones to the right

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