core/src/ons/gesture-detector.js
function on(element, type, handler, opt) {
    util.addEventListener(element, type, handler, opt, true);
  }
function on(element, type, handler, opt) {
    util.addEventListener(element, type, handler, opt, true);
  }
function on ( element , type , handler , opt ) { util . addEventListener ( element , type , handler , opt , true ) ; }
simple addEventListener wrapper
@param {HTMLElement} element
@param {String} type
@param {Function} handler
simple addEventListener wrapper