There is a small difference between the customervalidator client and the server in ASP. NET.

 

ASP. when customervalidator is used as a textbox verification control in. net, if we use a client to verify clientvalidationfunction, the input box will change to red when the input conditions do not meet the verification requirements, if we also set errormessage, other prompts will appear. However, if we use server-side verification separately, that is, to set its isvalid attribute through the background, we will get other error messages, but note that the text box of the corresponding error will not change to red at this time, which is the most significant difference.