Mithril Js Two Way binding with radio buttons (ES6)

controller.js

import VM from './viewModel';

export default class Controller {
	constructor(args) {
		var ctrl = this;
		ctrl.vm = new VM(args);
		return this;
	}
}

index.js

import view from './view';
import controller from './controller';

export default {
  view: view,
  controller: controller
};

view.js

export default function(ctrl) {
	let vm = ctrl.vm;
    var radioAttr = function(val) {
        return {
            id: val+"-select",
            checked: vm.radioVal() === val,
            type: "radio",
            name: "sccGroup",
            value: val
        };
    };
	return m('.game-component', [
	      // Create the radio group that listens to the events of radio buttons
        m('.r-group', {onchange: function(e) { vm.radioVal(e.target.value); } },[
            m('input',radioAttr("rock")),
            m('label',{for:"rock-select"}, [m('span'),"Rock"]),
            m('input',radioAttr("paper")),
            m('label',{for:"paper-select"}, [m('span'),"Paper"]),
            m('input',radioAttr("scissors")),
            m('label',{for:"scissors-select"}, [m('span'),"Scissors"])
        ]),
        m('button',{type: "submit", disabled: (vm.radioVal() === ''), onclick: function(){vm.radioVal('');}},"reset"),
        m('h3',vm.radioVal())
    ]);
}

viewmodel.js

export default class VM {
	constructor(args) {
		this.radioVal = m.prop('');//Create the data prop
		return this;
	}
	/**
	 * Data update event 
	 */
	change(e) {
		var v;
		v = e.target.getAttribute('value');
		return this.radioVal(v);
	}
};