formmethod [HTML5]
If the button is a submit button, this attribute specifies the HTTP method that the browser uses to submit the form. Possible values are:
post: The data from the form is included in the body of the form and is sent to the server.
get: The data from the form are appended to the form attribute URI, with a '?' as a separator, and the resulting URI is sent to the server. Use this method when the form has no side-effects and contains only ASCII characters.
If specified, this attribute overrides the method attribute of the button's form owner.