HTML and CSS Reference
The next feature that we will add is an essential feature of any form based web application:
the topic, HTML5 now contains a specification for form validation based on form attributes.
Although it may not be obvious, this has actually been implemented by default by adding
the required attributes to our input fields. If you press enter in the “Task” field without en-
tering any input you should see the following:
The message “Please fill out this field” is generated by HTML5 validation.
Despite the presence of HTML5 validation, we will not use it in this web application for two
1. All browsers do not support HTML5 validation; therefore it is necessary to rely on a poly-
fill for browsers that do not provide support.
they will only fire if the user clicks a submit button to post data to the server, or on a field
by field basis when the user presses enter in the field. Since we will never post data to the
server this is not helpful.
For these reasons, we will use the jQuery Validation library in this application. This can be
downloaded from here: