Let’s see some examples of using regular expressions for validating form field data.
Telephone numbers: As mentioned, the See the Pen Alpha-Numeric Character Validation Example by Site Point (@Site Point) on Code Pen.
A few months ago Sandeep introduced us to the HTML Constraint API, showing how we can use the new HTML5 input types and attributes to validate our forms in the browser with minimal Java Script.
Today I’m going to walk you through validating a simple booking form by using the Constraint API, and keep an eye on how you can make sure your forms stay accessible too.
In the past, client-side validation could only be achieved using Java Script or using libraries from frameworks (think j Query validation plugin).
But that is changing or rather has changed because validation can now be done using HTML5 without having to write complex Java Script validation code.
Today, regular expressions are included in most programming languages, as well as in many scripting languages, editors, applications, databases, and command-line tools.By adding this attribute to a form field, the browser requires the user to enter data into that field before submitting the form.This replaces the basic form validation currently implemented with Java Script, making things a little more usable and saving us some development time.In most cases, however, you should be able to use Google to search for the regular expression you want, or even use a tool to help you.This is a Boolean attribute used to indicate that a given input field’s value is required in order to submit the form.HTML5 includes a fairly solid form validation mechanism powered by the following .