Set Max Answers to Checkbox Question Dynamically Based on Previous Question Answer

Often survey builders wish to set the maximum answers a respondent can provide to a checkbox question dynamically based on the value entered in a previous Textbox question. You can achieve this, both for Checkbox questions on the same page and later pages, with a little bit of JavaScript. 

Check it out in an example survey!

OR

Add a survey with this setup to your account!

This script uses the following question types or actions:

• Textbox Question (for collecting the value for maximum)
• Checkbox Question 
• JavaScript Action

1. To get started create a Textbox question where you will collect the value that you will use in the maximum answers validation for the Checkbox question.
2. Next, create your Checkbox question. The questions can be on the same page or different pages.
3. Add a JavaScript action to the page with your Checkbox question.
4. Copy and paste one of the below scripts; there is one for when the Textbox and Checkbox questions are on the same page and one for when they are on different pages.

Script for when Textbox and Checkbox questions are on the same page:

$(document).ready(function(){
 
  var maxans;
 
  $(".max :text").blur(function(){
    maxans = $(this).val();
  });
 
  $(".checkboxQuestion").change(function(){
    var checked = $(".checkboxQuestion :checkbox:checked").length;
    if (checked == maxans) {
      $(".checkboxQuestion :checkbox:not(:checked)").attr("disabled",true);
    }
   
    if (checked < maxans) {
      $(".checkboxQuestion :checkbox").attr("disabled",false);
    }
  });
});

Once you have added the JavaScript to the page with your Checkbox question you need to add the CSS Class Names to each of the questions you wish to apply this script to.

• checkboxQuestion should be added to the Checkbox question
• max should be added to the Textbox question.

These classes should be added to the CSS Class Name field on the Layout tab of each question.

Script for when the Checkbox question is on a later page:

$(document).ready(function(){
 
  var maxans = '[question("value"), id="5"]'; //update id with ID of of checkbox question
 
  $(".checkboxQuestion").change(function(){
    var checked = $(".checkboxQuestion :checkbox:checked").length;
    if (checked == maxans) {
      $(".checkboxQuestion :checkbox:not(:checked)").attr("disabled",true);
    }
   
    if (checked < maxans) {
      $(".checkboxQuestion :checkbox").attr("disabled",false);
    }
  });
});

Once you have added the JavaScript to the page with your Checkbox question you will need to change the ID in the script to the ID of your checkbox question. Learn How to Find Question IDs.