Take a look at
http://bootstrapvalidator.com/
In our project we are using, Backbone validator, integrated with Bootstrap
https://github.com/thedersen/backbone.validation
Sample of integration Backbone.validation & Bootstrap
https://jsfiddle.net/thedersen/c3kK2/
That is if you are using Backbone :)
For bootstrapvalidator there is a callback method for validation
http://bootstrapvalidator.com/validators/callback/
From example:
  <input type="text" class="form-control" name="captcha"
                data-bv-callback="true"
                data-bv-callback-message="Wrong answer"
                data-bv-callback-callback="checkCaptcha" />
And JS
function checkCaptcha(value, validator) {
    // Determine the numbers which are generated in captchaOperation
    var items = $('#captchaOperation').html().split(' '),
        sum   = parseInt(items[0]) + parseInt(items[2]);
   return value == sum;
};
$(document).ready(function() {
    // Return a random number between min and max
    function randomNumber(min, max) {
       return Math.floor(Math.random() * (max - min + 1) + min);
    };
    // Generate a sum of two random numbers
    function generateCaptcha() {
        $('#captchaOperation').html([randomNumber(1, 100), '+', randomNumber(1, 200), '='].join(' '));
    };
    generateCaptcha();
    $('#callbackForm').bootstrapValidator();
});
You can implement arbitrary validation with it.
So your validation can be implemented through some global function
With HTML
  <input type="text" class="form-control" name="captcha"
                data-bv-callback="true"
                data-bv-callback-message="Wrong answer"
                data-bv-callback-callback="specialValidation" />
with JS
 function specialValidation(value, validator) {
    // Determine the numbers which are generated in captchaOperation
    var items = $('#otherField').txt();
    return value == sum;
};
And you need to be creative with element attributes, to link related elements correctly.