I would like to show an alert if no check box was checked in a field.
When the checkbox is valid (checked) the message is set to blank which tells the browser that it's ok for the form to be submitted.
Basically you don't want the form to be submitted unless this is checked.
Using vanilla Java Script we can prevent form submission as follows: All this does is confirm before submitting the form that the checkbox is checked.
Basically, when the checkbox is happy, the label is happy.
There are also clever ways of styling the label to look like a checkbox and hiding the actual checkbox so you can use your own graphic, font icon or CSS creation: , but actually toggling the checkbox in the background.