Inquiry into AngularJS data binding

Just dipping my toes into the world of Angular today. Found a tutorial at Angular JS in 30 mins

This little project involves setting up basic databinding in Angular. The code features an input box that updates with whatever is typed next to it. As someone coming from Java and Spring MVC, it all seems straightforward when the code looks like this:

index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Test Angular</title>
<script type="text/javascript" src="angular.min.js"></script>
<script type="text/javascript" src="app.js"></script>
<script type="text/javascript" src="maincontroller.js"></script>
</head>
<body>
 <div id="content" ng-app="SampleAngular" ng-controller="MainController">
  <input type="text" ng-model="inputVal">{{ inputVal }}
 </div>
</body>
</html>

app.js

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

maincontroller.js

app.controller("MainController", function($scope){
$scope.inputVal = "";

}
);

Surprisingly, even with an empty body for the controller:

maincontroller.js

app.controller("MainController", function($scope){


}
);

The same functionality still works in the view.

a) How does it work without a defined model in the controller? b) No errors or warnings indicate any issue - is this normal behavior for Angular?

Thanks in advance for any insights.

Answer №1

Here is an excerpt from the official documentation regarding the usage of ngModel:

It's important to note that ngModel attempts to bind to the property by evaluating the expression within the current scope. If the property does not already exist in this scope, it will be automatically created and added to the scope.

Answer №2

When utilizing ng-model in the view, Angular automatically generates a model value on the controller's scope. This default behavior does not result in any errors being thrown by Angular.

$scope.inputVal = "";

This line serves as more of an initialization for the variable that is being utilized.

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