Angular: Empty Fiddle

http://angularjs.org/

HTML

<div ng-controller="MyCtrl">
    <input ng-model="symbols" />
    <hr>
    {{ symbolsLength() }}
</div>

JavaScript

var myApp = angular.module('myApp', []);

function MyCtrl($scope) {
    $scope.symbols = 'four';
    
    var callsNum = 0;
    $scope.symbolsLength = function() {
        console.log('symbolsLength() calls: %d', ++callsNum);
        return $scope.symbols.length;  
    };
}