NgDirty in AngularJS

Anubhav Chaudhary
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Introduction

This article explains "ngDirty" in AngularJS.

ng-dirty in AngularJs helps to determine whether or not any changes have been made by the user at run time. If you are making changes from the code section then it's Ok for ng-dirty and it will not provide any type of error but if you are making changes at run time then it will show an error or display the text according to the CSS defined in the ng-dirty class.

ng-dirty is defined in the CSS as a class, then it is applied to the design section.

Now I will create a simple application and will show how you can use ng-dirty in your application.

Step 1

First of all you need to add an external Angular.js file to your application, "angular.min.js".

For this you can go to the AngularJS official site or can download my source code and then fetch it or you can click on this link to download it: ANGULARJS.

After downloading the external file you need to add this file to the Head section of your application.

<head runat="server">
<title></title>
<script src="angular.min.js"></script>
</head>

Step 2

Now after adding the External JS file the first thing you need to do is to add ng-app in the <HTML> Tag otherwise your application will not run.

<html ng-app xmlns="http://www.w3.org/1999/xhtml">

Now I will work on the JavaScript section for this application.

Write this code in the head section:

<script>
var mod = angular.module('mod', []);
function x($scope) {
$scope.autoChangeValue = 1;
setTimeout(function () {
$scope.autoChangeValue = 5;
$scope.$apply();
}, 1000);
}
</script>

Here I create a variable in which angular.module is defined.

After this a function named "x" is created, in the function a variable is used whose value is set to "1" but in the second or in the child function it's value is set to "5". So, two values are defined for the same variable but in two different functions.

Wherever these value will be bound, these values will be change after 1000 ms.

Step 3

Now I will work on the Body section, so write this code in the body:

<form id="form1" runat="server">
<p>If you make changes in the Textbox then background will change to Red</p>
<div ng-controller="x">
<div id="form">
<input type="text" ng-model="autoChangeValue"/>
</div>
</div>
</form>

Here I bound the first div to the function "x" using the ng-controller, in this div a TextBox is created bound to the "autoChangeValue".

What "autoChangeValue" will do is, it will firsty show the first value, "1", and after 1000 ms this value will be changed to "5" automatically. But if you try to make changes by yourself then the background will be changed to "red" as specified in the JavaScript section.

Now our application is completed and can be executed.

Output

On running the application you will get an output like this:

ngdirty

As I said in the beginning of this article, "1" will be shown initially but after 1000 ms it will be changed to "5".

ngdirty

But if you try to make changes in the textboxes manually then the red color will be applied to the background.

The complete code of this application is as follows:

<html ng-app="mod" xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
<script src="angular.min.js"></script>
<%--<script src="http://code.angularjs.org/1.0.3/angular-mocks.js"></script>--%>
<script>
var mod = angular.module('mod', []);
function x($scope) {
$scope.autoChangeValue = 1;
setTimeout(function () {
$scope.autoChangeValue = 5;
$scope.$apply();
}, 1000);
}
</script>
<style>
body { padding: 12px; }
.ng-dirty { background-color: red; }
</style>
</head>
<body>
<form id="form1" runat="server">
<p>If you make changes in the Textbox then background will change to Red</p>
<div ng-controller="x">
<div id="form">
<input type="text" ng-model="autoChangeValue"/>
</div>
</div>
</form>
</body>
</html>

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