Client-side validation

There are scenarios where we don't need to go to the server to validate the input data. In the preceding example of the server-side validation, we do not need to go to the server to verify whether the user has entered the data for the Name field. We can validate at the client-side itself. This prevents round-trips to the server and reduces the server load.

We are going to use JavaScript to validate the data from the client-side. JavaScript is a high-level, interpreted language which is primarily used in client-side programming.

Note

These days, JavaScript is also being used at the server-side as part of Node.js.

We are going to make a couple of changes in our View model (Index.cshtml file) to validate the form at the client-side:

1. Changes in the form: add the id attribute to all the span tags so that we can access this HTML element to display the HTML error message. On submission of the form, call a JavaScript function to validate the input data.

2. Add the script HTML element...