Show open textbox in a grid question

Introduction

In order to let the respondent specify an open text for Other option
As a questionnaire creator
I want to show a textbox next to "Other" text in a grid question

Example

Solution

Assuming that I have a single grid question labeled Q1, and I need to show the open text box in 3rd sub question (0-index)

Make the "Other" sub question NOT required

Create a dummy text question labeled Q1_Other

Add a piece of javascript to Q1

var errorMessage = "Please specify the open text";
var subQuestionIndex = 3;//0-based

quest.onInit = function()
{
   $("#grid_subquestion_text_"+ (subQuestionIndex+1)).append($("<input name='QUESTION.Q1_Other'>").val("{{Q1_Other}}"));
}

var oldCheck = questioncheck;
questioncheck = function()
{
   if (!oldCheck())
   return false;
   
   if ($("input:radio[name='QUESTION.Q1."+ subQuestionIndex + "'][checked=true]").length != 0)
   {
      if ($("input[name='QUESTION.Q1_Other']").val() == "")
      {      
         ErrorMessages.getInstance().showErrorMessage(errorMessage);
         return false;
      }
   }
   return true;
}

Add a CGScript to Q1_Other to remove double quotes

if (Q1_Other == empty)
return;
Q1_Other = stringReplace(Q1_Other, "\"", "'");