Angularjs form validation

AngularJS provides built-in form validation capabilities that can be used to validate user input in forms. Here are the steps to implement form validation in AngularJS:

1. Add the ng-app and ng-controller directives to your HTML markup.

<div ng-app="myApp" ng-controller="myCtrl">
  <!-- Form goes here -->
</div>

2. Add a form element to your HTML markup and give it a name using the name attribute.

<form name="myForm">
  <!-- Form fields go here -->
</form>

3. Add form input fields with the ng-model and name attributes.

<input type="text" ng-model="username" name="username" required>
<input type="email" ng-model="email" name="email" required>

4. Use AngularJS directives to display validation messages.

<div ng-show="myForm.username.$dirty && myForm.username.$invalid">
  <span ng-show="myForm.username.$error.required">Username is required.</span>
</div>
<div ng-show="myForm.email.$dirty && myForm.email.$invalid">
  <span ng-show="myForm.email.$error.required">Email is required.</span>
  <span ng-show="myForm.email.$error.email">Invalid email address.</span>
</div>

In the above example, the ng-show directive displays the validation message only when the input field is dirty and invalid. The ng-show directive is used with the $dirty and $invalid properties of the input field. The $dirty property indicates whether the user has interacted with the input field, and the $invalid property indicates whether the input field is invalid.

The ng-show directive is also used with the $error property of the input field, which contains an object of validation errors. In the above example, the ng-show directive displays the validation message only if the corresponding error exists in the $error object.

You can use other AngularJS directives like ng-class and ng-disabled to provide more interactive feedback to users.