Créer une simple captcha avec angularJS

Vous développez une application en Angular JS/Web API et vous devez protéger votre application de potentiels bots, spams ou abus ?

index.html

 <div ng-controller="Ctrl">     A simple captcha directive in AngularJS     <br><br>     <simple-captcha valid="captchaValid"></simple-captcha>     <br><br>     <div>valid: {{captchaValid}}</div> </div> 

Script.js

 var app = angular.module('app', []);  app.controller('Ctrl', function($scope){      });  app.directive('simpleCaptcha', function() {     return {         restrict: 'E',         scope: { valid: '=' },         template: '<input ng-model="a.value" ng-show="a.input" style="width:2em; text-align: center;"><span ng-hide="a.input">{{a.value}}</span> {{operation}} <input ng-model="b.value" ng-show="b.input" style="width:2em; text-align: center;"><span ng-hide="b.input">{{b.value}}</span> = {{result}}',         controller: function($scope) {                          var show = Math.random() > 0.5;                          var value = function(max){                 return Math.floor(max * Math.random());             };                          var int = function(str){                 return parseInt(str, 10);             };                          $scope.a = {                 value: show? undefined : 1 + value(4),                 input: show             };             $scope.b = {                 value: !show? undefined : 1 + value(4),                 input: !show             };             $scope.operation = '+';                          $scope.result = 5 + value(5);                          var a = $scope.a;             var b = $scope.b;             var result = $scope.result;                          var checkValidity = function(){                 if (a.value && b.value) {                     var calc = int(a.value) + int(b.value);                     $scope.valid = calc == result;                 } else {                     $scope.valid = false;                 }                 $scope.$apply(); // needed to solve 2 cycle delay problem;             };                                       $scope.$watch('a.value', function(){                     checkValidity();             });                          $scope.$watch('b.value', function(){                     checkValidity();             });                                                }     }; });