# UPC validation doesn't work if check digit is 0

Hello,

I have this algorithm which works for all 12-digit UPC codes, unless the final check digit is 0, in which case the validation always comes back as an invalid UPC code. If someone could look through and offer a suggestion or solution I would greatly appreciate it.

function checkUPCFormat12(formObj)
{
var temp = formObj.value.trim();

if (temp.length >11 && temp.length<= 12)
{
var myArray = formObj.value.split('');
step1 = 0;
var tempVar = myArray.length;
for (var i=0;i<tempVar;i=i+2)
{
step1 = step1 + +myArray[i];
}
var step2=step1*3;
step3 = 0;
for(var i=1;i<tempVar-1;i=i+2)
{
step3=step3+(+myArray[i]);
}
step4 = step2 + step3;
step5 = ((Math.floor(step4/10) + 1)*10) - step4;
if (step5 == myArray[myArray.length-1])
{
return true;
}
else
{
alert('You have entered an invalid 12-digit UPC Code. Verify and enter ALL numbers.')
return false;
}
}

Thanks,
R
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Commented:
0
Systems architectCommented:
From my point of view is check digit zero not allowed.
But if you want it, here my version:

<script>

function checkUPCFormat12(formObj){
//var num = formObj.value.split(""); // this is for form element
var num = formObj.split("");  // this is for String parameter
if(num.length!=12) return false;
var sum = 0;
for(var sum=i=0;i<11;i++){
if(i%2) sum += num[i]*1;
else sum += num[i]*3;
}
if((10-sum%10)%10==num[11]) return true;
return false;
}

</script>

0

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