What do you understand by validation of data in AngularJS?

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AngularJS enriches form filling and validation. AngularJS provides client-side form validation. It checks the state of the form and input fields (input, text-area, select), and notify the user about the current state. It also holds the information about whether the input fields have been touched, or modified, or not.

There are following directives that can be used to track error:

  • $dirty
    It states that the value has been changed.
  • $invalid
    It states that the value which is entered is invalid.
  • $error
    It states the exact error.
    Moreover, we can use novalidate with a form declaration to disable the browser’s native form validation.
  • n AngularJS, data validation refers to the process of ensuring that the data entered or manipulated by users meets certain criteria or constraints. This is typically done to ensure that the data is accurate, complete, and secure. AngularJS provides built-in mechanisms for both client-side and server-side validation.
    1. Client-Side Validation:
      • AngularJS uses directives like ng-model and ng-pattern to bind input fields to model properties and enforce client-side validation rules.
      • For example, you can use ng-required, ng-minlength, ng-maxlength, and ng-pattern directives to specify requirements for input fields.
      <form name=”myForm”>
      <input type=”text” ng-model=”user.username” ng-minlength=”3″ ng-maxlength=”10″ required />
      <span ng-show=”myForm.username.$error.required”>Username is required.</span>
      <span ng-show=”myForm.username.$error.minlength || myForm.username.$error.maxlength”>
      Username must be between 3 and 10 characters.
      </span>
      </form>

      </form>
      Server-Side Validation:

      • While client-side validation enhances user experience, it is crucial to perform server-side validation to ensure data integrity and security.
      • Server-side validation involves checking data on the server before processing or saving it, preventing malicious data from being submitted.
    2. javascript
      // Server-side validation example using Node.js and Express
      app.post('/submitForm', (req, res) => {
      const username = req.body.username;

      // Validate the username on the server side
      if (username.length < 3 || username.length > 10) {
      return res.status(400).send('Username must be between 3 and 10 characters.');
      }

      // Process and save the data if validation passes
      // ...
      return res.status(200).send('Form submitted successfully.');
      });
      if validation passes
      // ...
      return res.status(200).send('Form submitted successfully.');
      });

    In summary, data validation in AngularJS involves using client-side directives to enforce rules on the user interface and incorporating server-side validation to ensure data integrity and security on the server.