第二条说：若返回值介于-1和1之间则同等排序的位置，但其实自己试试，得到的结论却只是是否为正数和负数而已，好像不是以-1和1为分界线
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Array对象 </title>
<script type="text/javascript">
function sortNum(a,b) {
return a-b;
}
var myarr = new Array("80","16","16.5","50","6","100","1");
document.write(myarr.sort(sortNum));
</script>
</head>
<body>
</body>
</html>
