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My program should allow to display prompt box to enter values for a b and c and should display message in prompt box like "invalid number please enter number again" for a if a ==0 and a is not a number. Same with b , but b can be equal to 0 and has to be a number not any characters. and c can be equal to zero and has to be a number not any characters.

here is my code so far:

```
<script type="text/javascript">
var aValue;
aValue=window.prompt("What is a's value?","value goes here");
while(aValue==0 ||(isNan(aValue)))
{
aValue=prompt("Invalid number, enter a value again:", " value here");
}
var bValue;
bValue=window.prompt("what is b's value?","value goes here");
while(!(isNan(bValue)))
{
bValue=prompt("Invalid number, enter again:","value here");
}
var cValue;
cValue=prompt("what is c's value?","value goes here");
while(!(isNan(cValue)))
{
cValue=prompt("Invalid number,enter again:","value goes here");
}
</script>
```

How come it displays prompt box for a only? why am not I able to see prompt box for b and c?

Thanks,