Example of onstepcancel event

event-onstepcancel.js

var stepperElement = document.querySelector('.mdl-stepper');
// Select any step.
var step = stepperElement.querySelector('.mdl-step');

step.addEventListener('onstepcancel', function (event) {
  // When the step (this) action button/link with [data-stepper-cancel] attribute is clicked
  // you can redirect or do anything else.
  window.location.href = 'https://mysite.com';
});