title: how to call a method when change in field using angular JS?
body: <p>I am entering numbers in two fields and showing another field using arithmetic calculation.In that I wanna one call and that calculation and want to calculate using input type=" text" only not a number.</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.4/angular.min.js"&gt;&lt;/script&gt;
  
  &lt;body&gt;
  
      &lt;div ng-app="myApp" ng-controller="myCtrl"&gt;
  
          First Name:
          &lt;input type="text" ng-model="firstvalue"&gt;
          &lt;br&gt; Last Name:
          &lt;input type="text" ng-model="lastvalue"&gt;
          &lt;br&gt;
          &lt;br&gt;
          &lt;br&gt; Total:
          &lt;input type="text" ng-model="total=firstvalue + lastvalue" ng-change="changed()" disabled="disabled"&gt;
          &lt;br&gt;
      &lt;/div&gt;
  
      &lt;script&gt;
          var app = angular.module('myApp', []);
          app.controller('myCtrl', function($scope) {
              $scope.changed = function() {
                  alert("Total" + $scope.total);
              };
          });
      &lt;/script&gt;
  
  &lt;/body&gt;
  
  &lt;/html&gt;
  </code></pre>
  
  <p>i want to sum those two value.want show the sum in third field and also when change the third field need to call one function like ng-change that field need to disable.</p>