Validate email specified as an open text of a single question

Challenge

In order to secure my questionnaire's input
As a CGS writer
I want to validate an email specified as an open text of a single question
Example

Solution

var qLabel = "Q1";//question's label
var openAnswerValue = 1;//the value of answer option which has open text
var ErrorMessage_InvalidEmail = "Invalid email.";//error message in your needed language
   
var oldQuestionCheck = this.questioncheck;
questioncheck = function()
{
   if (!oldQuestionCheck())
   return false;
   
   var email = $("input[name='QUESTION." + qLabel + ".Open." + openAnswerValue +"']").val();
   
   if (!validateEmail(email))
   {
      ErrorMessages.getInstance().showErrorMessage(ErrorMessage_InvalidEmail);
      return false;
   }
   
   return true;
}