Writing an adding function in AngularJS

Question

I'm new to AngularJS and I am doing some tutorials to get in touch with it. While I'm doing the tutorials I have modified the code a bit to get a better feeling of what's behind. My code consists of two parts, which have nothing to do with each other.

The first one is a simple user input and based on that a list gets filtered. This is working fine.

However, in the second part I was trying to implement a simple adding function where the user can give an input and based on that the sum of two numbers is calculated. This part is not working at all. The numbers are being recognised as strings. The code is basically from this source here. When I copy the whole code and run it, it works fine, but when I modify it a bit it doesn't.

I want to understand why my code isn't working. To me there is nearly no difference. So I think that I eventually misunderstood the concept of angularjs. But I can't figure out where the error could be.

<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.6/angular.min.js"></script>
<script type="text/javascript">
    function TodoCtrl($scope) {
        $scope.total = function () {
            return $scope.x + $scope.y;
        };
    }
</script>
</head>
<body data-ng-app>
    <input type="text" ng-model="name">{{name}}
    <div data-ng-init="Names=['Arthur', 'Bob', 'Chris', 'David', 'EDGAR']">
        <ul>
            <li data-ng-repeat="naming in Names | filter: name ">{{naming}}</li>
        </ul>
    </div>

    <div data-ng-controller="TodoCtrl">
        <form>
        <input type="text" ng-model ="x">{{x}}
        <input type="text" ng-model ="y"> {{y}}
        <input type="text" value="{{total()}}"/>
        <p type= "text" value="{{total()}}">value</p>
        </form>
    </div>
</body>
</html>

the code in the article you linked was using `angularjs 1.0.5`, in ***2013***. that syntax hasn't been valid since `angularjs 1.2`, in 2015. — Claies, Sep 16 '17 at 15:21

Matthew Cawley · Accepted Answer · 2017-09-16T15:32:05.647

Several things to change...

First you need to create a module:

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

Then you need to define a module e.g. myApp on the ng-app directive.

<body data-ng-app="myApp">

Then you need to add TodoCtrl to the module:

app.controller("TodoCtrl", TodoCtrl);

Also check that both $scope.x and $scope.y have values, and make sure that they are both parsed as integers, otherwise you will get string concatenation ("1"+"1"="11") instead of addition (1+1=2)!

$scope.total = function () {
  return ($scope.x && $scope.y) 
    ? parseInt($scope.x) + parseInt($scope.y)
    : 0;
  };

<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.6/angular.min.js"></script>
<script type="text/javascript">
(function(){

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

    app.controller("TodoCtrl", TodoCtrl);

    function TodoCtrl($scope) {
        $scope.total = function () {
            return ($scope.x && $scope.y) 
              ? parseInt($scope.x) + parseInt($scope.y)
              : 0;
        };
    }
}());
</script>
</head>
<body data-ng-app="myApp">
    <input type="text" ng-model="name">{{name}}
    <div data-ng-init="Names=['Arthur', 'Bob', 'Chris', 'David', 'EDGAR']">
        <ul>
            <li data-ng-repeat="naming in Names | filter: name ">{{naming}}</li>
        </ul>
    </div>

    <div data-ng-controller="TodoCtrl">
        <form>
        <input type="text" ng-model ="x">{{x}}
        <input type="text" ng-model ="y"> {{y}}
        <input type="text" value="{{total()}}"/>
        <p type= "text" value="{{total()}}">value</p>
        </form>
    </div>
</body>
</html>

score 2 · Answer 2 · answered Sep 16 '17 at 15:37

As mentioned in the above two answers adding TodoCtrl as controller instead function will make the snippet work.

REASON:

Angularjs framework above 1.3 does not support global function which means declaring controller as function wont work.

In your code snippet, you are using angular version 1.5, which needs the controller to be defined.

DEMO

angular.module("app",[]) 
.controller("TodoCtrl",function($scope){
      $scope.x = 0;
      $scope.y = 0;
        $scope.total = function () {
            return parseInt($scope.x) + parseInt($scope.y)
     }; 
})

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="app" >
    <input type="text" ng-model="name">{{name}}
    <div data-ng-init="Names=['Arthur', 'Bob', 'Chris', 'David', 'EDGAR']">
        <ul>
          <li data-ng-repeat="naming in Names | filter: name ">{{naming}}</li>
        </ul>
    </div>
    <div data-ng-controller="TodoCtrl">
        <form>
        <input type="text" ng-model ="x">{{x}}
        <input type="text" ng-model ="y"> {{y}}
        <input type="text" value="{{total()}}"/>
        <p type= "text" value="{{total()}}">value</p>
        </form>
    </div>
</div>

score 1 · Answer 3 · answered Sep 16 '17 at 15:18

you need to define the TodoCtrl as controller instead function

.controller("TodoCtrl",function($scope){
          $scope.x = 0;
          $scope.y = 0;
            $scope.total = function () {
                return parseInt($scope.x) + parseInt($scope.y)
            }; 
 })

Demo

angular.module("app",[]) 
.controller("TodoCtrl",function($scope){
      $scope.x = 0;
      $scope.y = 0;
        $scope.total = function () {
            return parseInt($scope.x) + parseInt($scope.y)
        }; 
     
})

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="app" >
    <input type="text" ng-model="name">{{name}}
    <div data-ng-init="Names=['Arthur', 'Bob', 'Chris', 'David', 'EDGAR']">
        <ul>
            <li data-ng-repeat="naming in Names | filter: name ">{{naming}}</li>
        </ul>
    </div>

    <div data-ng-controller="TodoCtrl">
        <form>
        <input type="text" ng-model ="x">{{x}}
        <input type="text" ng-model ="y"> {{y}}
        <input type="text" value="{{total()}}"/>
        <p type= "text" value="{{total()}}">value</p>
        </form>
    </div>
</div>

Thanks, this helped, but how does the code from the source [https://stackoverflow.com/questions/15648711/angular-js-adding-two-numbers-issue] work for me, even though I didn't define "TodoCtrl" as controller? — Pluxyy, Sep 16 '17 at 15:27
it doesn't even define the `angular.module` also. if you are using angular you need to follow the protocols provided by the framework. This is the proper way define the module — Sachila Ranawaka, Sep 16 '17 at 15:36

Writing an adding function in AngularJS

3 Answers3