mathPtcha.js

function onSuccess(){
  $('form').attr('action', 'foo');
}

function makeEquation(successCallback){
  var words = ['one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten'];
  var left = Math.floor(Math.random() * 10 + 1);
  var right = Math.floor(Math.random() * 10 + 1);
  var question = words[left-1] + ' + ' + words[right-1] + ' = ? (example: one + two = 3)';
  return {
    question: question,
    verify: function verify(answer){
      var answer == left + right;
      if(successCallback){
        (successCallback || function(){}).call()
      }
    }
  };
}

var captcha = makeEquation(onSuccess);
captcha.question; // "ten + six = ? (example: one + two = 3)"
captcha.verify(16) // calls success callback
captcha.verify(14) // does nothing