Here's a shortened form written in javascript:
function sort( a1, a2 ) {
var i = 0
, j = 0
, l1 = a1.length
, l2 = a2.length
, a = [];
while( i < l1 && j < l2 ) {
a1[i] < a2[j] ? (a.push(a1[i]), i++) : (a.push( a2[j]), j++);
}
i < l1 && ( a = a.concat( a1.splice(i) ));
j < l2 && ( a = a.concat( a2.splice(j) ));
return a;
}