title: How to watch multiple property change using angularjs
body: <p>I have two properties to watch for and update the third depends on change in first two.
  here is my code
  Can anyone help me on this?</p>
  
  <pre><code>return {
          context: 'prop1',
          watch: [
                  {
                     property: ["prop2","prop3"], // this to watch for
                     update: [
                     {
                         dest: "prop4", // update this prop based on change in prop2 and prop3
                         src: [function (value) {
                             if (value.prop2change === 'thisvalue') { 
                                 return prop3changevalue;
                             }
                             else
                                 return 0;
                         },"newValue"]
                     }
               }
           ]
       }
  </code></pre>