We are having a discussion whether or not we should force our text inputs to disallow incorrect type of entries to be entered. In other words if I have some kind of validation on input field (let's say I only allow enter correct names, like no triple letters in a row, no numbers etc..) it will not allow user to type in those incorrect entries i.e. if I wanted to type in Jooohn my cursor would stop at Joo and it doesn't matter how many times I would press o key it would not give me any feedback and input field would stay with Joo

My question - are there any pros for doing it like this way?

I can only come up with cons:

  1. User can get frustrated because he does not get any feedback why cursor is not moving anywhere
  2. In some cases such a behaviour can force user to think that his machine is not responding
  • 3
    If you can't think of any pros to doing it, where did the idea come from in the first place?
    – JonW
    Mar 5, 2014 at 14:01
  • With regards to con2: if you get sound feedback by typing wrong as well the user will understand that he is doing something wrong. But unless you explicitly tell him on screen what he is suppose to be entering restricting input is a bad idea. Mar 5, 2014 at 14:03
  • @JonW Idea comes from above and I'm trying to gather more cons to persuade doing it otherwise. Mar 5, 2014 at 14:31
  • @VytautasButkus: Pity you have to come up with reasons not to do something when you've not been given any solid reasons to do it in the first place. I'd go back to those above and ask them what the business requirement is that this suggestion helps meet. If they don't have a valid business case for doing it then it is just wasting everyone's time proceeding with it. (But yes, sometimes convincing those above things like this isn't so easy!).
    – JonW
    Mar 5, 2014 at 14:38

2 Answers 2


The only pro to this is a reduction on errors in the Database side.

There is no Pro on the human side unless you include the additional requirement of providing expectation to the user of what is happening.

If the user starts typing "Joo" and can't type "Jooohn" at that point when the user presses the extra "o" some kind of messaging should come up saying something like "Please check your spelling." (Sorry I'm not a copywriter.) Providing feedback to the end user is keystone to this concept working.

I've seen this type of thing before on forms. It only makes sense if the syntax format is strict such as in Postal Code or ZIP code entry.

You cannot place this limit on Name Input boxes because the strings could contain any number of characters. Here are possible scenarios why:

  1. The user's name actually contains 3 of the same letters in a row.
  2. The user's name could contain less than 3 characters.

There is technically no way to determine what "Correct Names" are because they vary more than colours in the rainbow and can include a variety of character types, accents, etc..


I think having inline / realtime validation without any visual feedback is not good UX.

Can't see any pros, and I don't think anyone else can either. (Or it might be a pro if it's less work to write validation that doesn't give feedback, but that is not pro from the UX perspective...)

  • yeah use something like ketchup.js to add a little bloop red thing to let people know things are not okay. Mar 5, 2014 at 14:55
  • 1
    Ok, then I misread the question, I understood that it doesn't give any visual feedback, only that it doesn't let users write 3 repeated letters. But is there any explanation in the little bloop red or is it just sign of "not ok". If someone would really have a name like Jooohn in the Netherlands or something, then he might start going nuts if he can't type his name and it keeps only giving a hint that "not ok".
    – Samuel M
    Mar 5, 2014 at 15:07
  • I also misread the question. It's just a notification, and you can put any text in there, such as "Are you sure your name is Jooohn?" etc Mar 5, 2014 at 18:01

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