How to apply input mask when the entry length is not fixed?

what if the entry length is not fixed? example 12AA12345678

The last set of numbers' length is not fixed. it could be less or more? how to apply the mask here? Thanks!

Could you please provide more information on which field you wish to apply the mask? Also, please share the URL of the form that you are working on.

Im trying to make a field with a mask where entry must be like this...

Examples:

12AB12345678

19CD8765

First 2 chars - numbers

3rd and 4th chars - alphabets

Then all the next characters are numbers but the LENGTH is different from one another. Some has 4 digits some has more. Example given above are showing what i meant.

I have no form url to share coz I didnt complete my form yet.

Thanks!

Input mask is used when a specific format is required. Unfortunately, it is not possible to have a variable length of the numbers.

You may consider to use our Masked Input widget, which may give you more flexibility. You can find here:

https://widgets.jotform.com/widget/masked_input

Let us know if you need any further assistance.

Can you please try to use the format below in the Input Mask field?

##@@[#][#][#][#][#][#][#][#][#][#]

Please give it a try and let us know how it works for you.

We will wait for your response.

I used the following for a phone number field and it worked:

 ###-###-#### [***. ][*][*][*][*][*][*]

And I put this in the placeholder on the advanced tab of the field:

Ex: 304-123-1234 Ext. 12 (enter numbers and letters only - Extensions are optional)

Glad it worked. Is there anything else we could assist you with?

No thank you; and thank you for asking.
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IvayloK, your solution was a hit! Thank u! It did work!

Thanks everyone for taking time! 

Cheers,