<aura:component>
    <aura:handler name="init" value="{!this}" action="{!c.doInit}" />
    <form action=" url" method="post" I'd="form"/>
    <Inputtype="submit",value="submit" >
</aura:component>

doInit: function(component, event, helper)
{
    $( "form" ).submit(function( event ) {
        event.preventDefault();
        return false;
    });
}

submitForm : function () {
            $( "form" ).submit(function( event ) {

       event.preventDefault();
       return false;
    });
        }

<input type="submit" name="submit" onsubmit="submitForm()"/>

$("form").submit(function( event ) {
              event.preventDefault();
              url = $form.attr( 'action' );
              var posting = $.post( url, { email: $('#email').val() } );
              posting.done(function( data ) {
               alert("success")
                   });
               alert("submitted")
                 });

$( "form" ).submit(function( event ) {

   event.preventDefault();
   return false;
});

<form action="javascript:return false" aura:id="sendNotificationForm" ... >

({
    ...
    ,sendNotification: function(component, event, helper) {
        ....

        event.preventDefault();

        ...
    }
    ...
})