The constraint validation API adds the following properties / methods to DOM nodes.
The property of a DOM node contains the message the browser displays to the user when a node's validity is checked and fails.
The validation of data that has been entered in a form is necessary in most cases. For example, what good is holding a contest or sweepstakes if you can’t notify the winner, because he or she entered an invalid telephone number or an incorrect address.
Their have common purpose — to prevent wrong user input as soon as possible.
And we will see what it takes to implement it in our “Add user form” example.
”, this should be very important for your web site! There are two types of validation; client side and server side.
For reference, client side means that you are depending on what browser the user is currently using.
When in comes to validating forms, there are basically two techniques you can use: 1) Server-side validation and 2) Client-side validation.