Javascript数组(array) sort方法的解释和分析

function desc(x,y)
...{
if (x > y)
return -1;
if (x < y)
return 1;
}
function asc(x,y)
...{
if (x > y)
return 1;
if (x < y)
return -1;
}
arrA.sort(desc);    // sort by desc
document.writeln(arrA);
document.writeln("<br>");
arrA.sort(asc);    //sort by asc
document.writeln(arrA);