What makes anonymous functions a must-have in AngularJS development?

Many tutorials on AngularJS recommend using anonymous functions instead of normal functions, like function name(para1) {}. For example, take a look at this link: http://www.w3schools.com/angular/tryit.asp?filename=try_ng_controller_property

I tried changing to a normal function, but it didn't work. Can anyone provide guidance on this issue? Thank you.

<div ng-app="myApp" ng-controller="personCtrl as main">

First Name: <input type="text" ng-model="firstName"><br>
Last Name: <input type="text" ng-model="lastName"><br>
<br>
Full Name: {{main.fullName()}}

</div>

<script>
var app = angular.module('myApp', []);
app.controller('personCtrl', function($scope) {
    $scope.firstName = "John";
    $scope.lastName = "Doe";
    function fullName() {
        return $scope.firstName + " " + $scope.lastName;
    };
});
</script>

Answer №1

One of the core concepts in AngularJS is the use of `$scope`, an object that contains all the fields and functions needed for referencing in templates.

If you fail to attach a function to the `$scope` object, Angular will not be able to call it. Therefore, it is crucial to include everything required in the controller function to the `$scope` object provided by the framework. This allows easy access to fields and functions from the template. While Angular can evaluate expressions within directives like `ng-model` or `{{ }}`, it may struggle to understand expressions like `fullName()` if they are not properly attached to the `$scope` object as shown in your example link, or when written as `main.fullName()`.

To delve deeper into the concept of `$scope`, check out the official Angular docs on scopes.

Answer №2

If you want to follow a good practice, consider declaring your functions and then assigning them to the $scope, perhaps in the controller's initialization. This approach will make it clearer when you revisit your code. Here is an example:

<!DOCTYPE html>
<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.8/angular.min.js"></script>
<body>

<div ng-app="myApp" ng-controller="personCtrl">

First Name: <input type="text" ng-model="firstName"><br>
Last Name: <input type="text" ng-model="lastName"><br>
<br>
Full Name: {{fullName()}}

</div>

<script>
var app = angular.module('myApp', []);
app.controller('personCtrl', function($scope) {
    $scope.firstName = "John";
    $scope.lastName = "Doe";
    $scope.fullName = fullName; //<-- function assigned here

    function fullName() {
        return $scope.firstName + " " + $scope.lastName;
    };
});
</script>

</body>
</html>

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