Trending September 2023 # How Angular Cli Works With Examples? # Suggested October 2023 # Top 14 Popular

You are reading the article How Angular Cli Works With Examples? updated in September 2023 on the website Lanphuongmhbrtower.com. We hope that the information we have shared is helpful to you. If you find the content interesting and meaningful, please share it with your friends and continue to follow and support us for the latest updates. Suggested October 2023 How Angular Cli Works With Examples?

Introduction to AngularJs ng-change

AngularJS ng-change is an In-Built AngularJS directive that can be used on HTML view Page. As the name says, whenever this directive is placed as an attribute within an HTML element, then anytime the HTML element experiences a change in model value, it invokes the ng-change directive, which calls the function or executes the expression defined inside the ng-change directive. In this topic, we are going to learn about AngularJs ng-change.

Start Your Free Software Development Course

Web development, programming languages, Software testing & others

Here are the following syntax mentioned below

Using with INPUT Element

<input type="email" ng-change="onChangeOfEmail()"

Using with SELECT Element

<select ng-model="selectedSubject" ng-change="onChangeOfSubjects()"

Using with TEXTAREA Element

Along with these, ng-change directives can also be used with input type email, tel, checkbox, radio buttons, name, and all types of HTML tags that accept user input and have user interaction.

How Angular CLI works?

AngularJS ng-change directive comes with few limitations as well –

If the newly changes model value is not a valid value, then ng-change won’t get triggered as the ng-model default value goes to null

If the Model value is changed in Controller and NOT in view, then ng-change won’t get triggered as it’s tightly coupled with the view

If the Model value returned from the $parsers transformation pipeline remains unchanged, then ng-change won’t get triggered

Examples of AngularJs ng-change

Different examples are mentioned below:

Example #1

Index.html

.subject-dropdown { width: 80%; height: 35px; line-height: 35px; color: primary-blue; border: 1px solid primary-blue; margin-left: 40px; } .text-msg { margin-top: 20px; font-weight: bold; text-align:center; color: red; } <select class="subject-dropdown" ng-model="selectedSubject" ng-change="onChangeOfSubjects()" and subject Code is {{subjectCode}}

chúng tôi

angular.module('subjectapp', []) .controller('SubjectController', function($scope) { $scope.subjects = [{'key': '01', 'value': 'English'}, {'key': '02', 'value': 'History'}, {'key': '03', 'value': 'Mathematics'}, {'key': '04', 'value': 'Science'}, {'key': '05', 'value': 'French'}]; $scope.onChangeOfSubjects = onChangeOfSubjects; function onChangeOfSubjects() { $scope.subjectValue = $scope.selectedSubject.value; $scope.subjectCode = $scope.selectedSubject.key; } });

In the above example, we are trying to display a list of Subjects on UI using a select tag so that it will display in the dropdown with various subjects available. We have added an ng-change directive to the select HTML tag, so as soon as the dropdown value is changed from its current ng-model value, then ng-change will get triggered. This ng-change will execute function onChangeOfSubjects which is defined in the corresponding controller. Also, as the Subject is an object of key-value pair, we are displaying the name of the selected subject and its corresponding Subject code. Make sure to include the AngularJS dependency in the Script tag so that you will be able to use the ng-repeat directive of AngularJS.

ng-change="onChangeOfSubjects()"

Here onChangeOfSubjects method will get executed whenever ng-change is triggered. It can accept any number of parameters, and we are not passing any as we will be using scope model value in the controller.

ng-model="selectedSubject"

Just by using a few simple and easy CSS styling, we will be able to view the output of the above code.

Output:

Example #2

Index.html

.email-input { width: 80%; height: 35px; line-height: 35px; color: primary-blue; border: 1px solid primary-blue; margin-left: 40px; } .text-msg { margin-top: 20px; font-weight: bold; text-align:center; color: Blue; } <input class="email-input" type="email" ng-change="onChangeOfEmail()"

chúng tôi

In the above example, we are trying to accept input as an Email id on UI using the INPUT tag so that it will display the email id. We have added an ng-change directive to the input HTML tag, so as soon as the email id is entered or changed from its current ng-model value, then ng-change will get triggered. This ng-change will execute the function onChangeOfEmail, which is defined in the corresponding controller. In this controller method, we will validate whether the email id is a valid email id based on the pattern for defined. If it’s valid, we assign the scope variable value as valid and if an invalid, the invalid string is assigned to validity value. Make sure to include the AngularJS dependency in the Script tag so that you will be able to use the ng-repeat directive of AngularJS.

ng-change=" onChangeOfEmail ()" ng-model=" emailValue "

As discussed above, ng-change can only work with the ng-model in this, so we have used the ng-model in select.

Just by using a few simple and easy CSS styling, we will be able to view the output of the above code.

Output:

Conclusion

The ng-change directive in AngularJS is another most widely used and useful In-Built AngularJS directive, which can be used with an HTML element to handle any input change on UI and perform required operation in the controller by using a function call. Again, knowing the syntax is all that is needed, and you are ready to go.