JavaScript将UPC转换成ISBN的代码
if (indexisbn.indexOf("978") == 0) {
isbn = isbn.substr(3,9);
var xsum = 0;
var add = 0;
var i = 0;
for (i = 0; i < 9; i++) {
add = isbn.substr(i,1);
xsum += (10 - i) * add;
}
xsum %= 11;
xsum = 11 - xsum;
if (xsum == 10) { xsum = "X"; }
if (xsum == 11) { xsum = "0"; }
isbn += xsum;
}
