sort.js

var i, j,
    arr = [2,5,1,0],
    max = 0,
    n   = arr.length;

for (i = 1; i < n; i++)
    for (j = 0; j < n - 1 ; j++) {
        max = arr[j + 1];
        
        if (arr[j] > max) {
            arr[j + 1]  = arr[j];
            arr[j]      = max;
        }
    }