UPC Validation and UPC-A to UPC-E conversion

function getUPCCheckDigit(x)

{

x = '' + x; // Make sure x is a string

x = x.split('');

var sum = 0;

for (var i=0, len=x.length; i<len; ++i){

(i%2)? sum += +x[i] : sum += x[i]*3;

}

var z = sum%10;

z = (z)? 10-z : z;

if(z==x[length])

{

return true;

}

else

{

return false;

}

}

function UPCa2e(x)

{

x += ''; // Make sure x is a string

var y = x.substring(3,9);

return '0' + y + getUPCCheckDigit(y);

}