How to change the text the user puts in, if the text is 'incorrect'?

[logistics277258970]

Good evening

I am wondering if there is a way to change text that the user puts in into "ERROR" if that said text is wrong.

For more clarification, I am trying to make a script where, if the user puts in the code "Z85" in a field where it shouldn't be there, it'll change the "Z85" into "ERROR."

[try67 · Accepted solution]

As the custom validation script of that field enter this code:

if (event.value=="Z85") event.value = "ERROR";