onsubmit attribute is used on the
form element only. Its purpose is to capture
the moment when the form is submitted, following the moment when the user
activates the form’s Submit
This attribute is used
almost exclusively for the purpose of running form validation scripts. In
such scenarios, the user fills in the form and clicks submit, at which
onsubmit attribute triggers the form
validation routine, and the form is either submitted, or cancelled because
of an error of which the user is alerted:
<form name="frmPersonalDetails" action="/personal.php" onsubmit="checkPersonalDetails();"> ⋮ </form>
This attribute has no fixed value.
It’s up to the author to decide on the scripting that’s included here, be
that a call to one or more defined functions, or a simple
Every browser listed supports this attribute. However, inline event handlers such as this should be avoided. In the same way that inline CSS styles are frowned upon but externally defined CSS styles are considered good practice, inline event handlers should be stripped out and replaced with events attached unobtrusively through the DOM.