Validating text box entries
If your web browser supports HTML5, it will not allow you to submit the form without entering text into the input field.
For example, providing users with the option to check the postal address that they provided can be useful before a purchase is completed.The first project is a class library called "Reg Ex Controls" which contains a class called "Reg Ex Text Box"; this class is an extended text box control that provides the means to store a regular expression and to test the text box text against the regular expression.The second project is a test windows form application called "Test Reg Ex Controls"; this project contains a single windows form that shows five examples of the extended text box control in use in conjunction with an error control.Note that the label also displays “(required)”, to inform users that don’t use assistive technology or use older web browsers that do not support the HTML5 attribute informs assistive technologies about required controls so that they are appropriately announced to the users (as opposed to validating the input).Most current web browsers automatically set its value to .HTML5 input types are displayed as simple input fields in older web browsers that do not support these HTML5 features.
The example below shows these HTML5 input types in action.
Client-side validation alone does not ensure security; therefore data needs to be validated on the server-side as well.
Forms frequently include required input that needs to be clearly identified using labels.
In addition to providing instructions, validate user input to help users avoid mistakes.
HTML5 defines a range of built-in functionality to validate common types of input, such as email addresses and dates.
This means that validation needs to be carried out server-side as well.