Execute code after HubSpot form submit

gistfile1.txt

hbspt.forms.create({
	...
	onFormReady: function($form, ctx) {
	    
	    $form.submit(function(){

	        //synchronous delay
	        HSPopup.pause(300);

	        //Your code goes here

	    });
	}					
});

function pause(milliseconds) {
    var dt = new Date();
    while ((new Date()) - dt <= milliseconds) {}
}