Preventing redundant parsing

The $parse operation can often be unnecessarily repetitive in certain situations. If your application scales to the point where this redundancy is starting to become a performance factor, then the parsing can be refactored in order to prevent reparsing the same expression over and over.

Getting ready

Suppose that your application resembles the following code:

(index.html)

<div ng-app="myApp">
  <div ng-controller="OuterCtrl">
  <div ng-repeat="player in data.playerIds" 
       ng-controller="InnerCtrl">
  </div>
  </div>
</div>

(app.js)

angular.module('myApp', [])
.controller('OuterCtrl', function($scope, $log) {
  $scope.data = {
    playerIds: [1,2,3]
  };
})
.controller('InnerCtrl', function($scope, $log, $parse) {
  $scope.myExp = function() {
    $log.log('Expression evaluated');
    return 'watchedValue';
  };
  $scope.$watch(
...