When you have a web form and one of the fields to be entered is the Chromosome Number, you’d be wise to check that the user does not enter the wrong thing (e.g. ‘0’ , ‘X1’, ‘21.13’). Thus a validation check may save you some headaches.

I set out to find the appropriate regular expression in Javascript that returns an error when the chromosome entered is not 1-22 or X or Y. It turns out that for me it wasn’t that easy to solve this little problem. I searched in Google to see if anyone had posted the solution to the problem and found nothing meaningful.

Therefore I paste below the solution I wrote. I must admit that it is rather ugly the fact that I have to use two *if* expressions. I would appreciate if any reader posted a more elegant solution. But for now, this code seems to work fine.

function notValidChr(field)
{
// Field may start with a number or optionally two
if ( field.value.match(/^\d\d?$/)
// Is it an integer greated than 0?
&& (0 < parseInt(field.value)
// Is it an integer smaller than 23?
&& parseInt(field.value) <23
)
)
{
// If all conditions above are met, notValidChr is not true
return false;
}
// Check if it is a valid X or Y chromosome
if (field.value.match(/^[XY]$/)) {
// If so notValidChr is not true
return false;
}
// Yes! the text entered is not a valid chromosome
return true;
}

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Ah my bad I misread the following

“when the chromosome entered is not 1-22 or X or Y.” to mean it would always include the an X or Y

Hope it helps anyway

Your contribution did help indeed. Thanks a lot!

Manuel

thanks Jeff,

your solution does not match numbers like 1, 13, 22. But it matches something like 22x or 3y.

A modified version of your solution seems to work better:

^([1-9]|1[0-9]|2[0-2]|[X|Y])$

Would the following regex help? Haven’t tried it in JS, but should just work….

^([1-9]|1[0-9]|2[0-2])(X|Y)$