We will explain that in detail in the next section.
This is very poor usability, and directly contravenes accessibility guidelines.
What we’re going to do in this article is far less intrusive.
For legacy browsers that don’t implement these attributes, we can use their values as the basis of a polyfill.
We can also use them to provide a more interesting enhancement – instant form validation.
Now that we have the static code, we can add the scripting.
The first thing we’ll need is a basic property (the dot property only matches states which are set through scripting).
Ideally, users fill in the form with necessary information and finish the job successfully. These requirements turned into the main characteristics of this solution: element (type=email, number, …), we also have constraint validation (required, maxlength, …) to ease the work of checking the form content on the client side.
Constraint validation is an algorithm browsers run natively when a form is submitted to determine its validity.