JarCastingquickselect 
A tiny and fast selection algorithm in JavaScript (specifically, Floyd-Rivest selection).
quickselect(array, k[, left, right, compareFn]);
Rearranges items so that all items in the [left, k] are the smallest. The k-th element will have the (k - left + 1)-th smallest value in [left, right].
array: the array to partially sort (in place)k: middle index for partial sorting (as defined above)left: left index of the range to sort (0by default)right: right index (last index of the array by default)compareFn: compare function
Example:
var arr = [65, 28, 59, 33, 21, 56, 22, 95, 50, 12, 90, 53, 28, 77, 39];
quickselect(arr, 8);
// arr is [39, 28, 28, 33, 21, 12, 22, 50, 53, 56, 59, 65, 90, 77, 95]
// ^^ middle index