A simple example to explain inline validations using HTML as a language without using window.alert .?

Question

validation done at the client side if the user enters the data which is not correct.
The error should be displayed just below the (ex text box -- invalid)

Answer 1

Here is an example of what you are looking for using javaScript and CSS style.

The second link is the tutorial, so I guess you have some reading to do if you want to progress on your own.