AngularJS Model Sample

HTML

<div ng-app="ez-calc" ng-controller="CalculatorController">
    <h3>Calculadora</h3>
    <input type="text" ng-model="a" placeholder="Um número"/>
    <input type="text" ng-model="operation" placeholder="Operação"/>
    <input type="text" ng-model="b" placeholder="Outro número"/>
    <br/><br/><br/>
    <span>Resultado : {{calculator[operation](a, b)}}</span>
</div>

JavaScript

var app = angular.module('ez-calc', []);

app.service('Calculator', function() {
    var add = function(a, b) {
        if (!a || !b)
            return;

        return Number(a) + Number(b);
    };
    
    return {
        "+" : add
    }
});

app.controller('CalculatorController', function($scope, Calculator) {
    $scope.calculator = Calculator;
});