Showing dependency on data attribute in Router.route, in order to get back button functionality

index.html

<template name="layout">
    {{#ionBody}}
      {{> ionNavBar class="bar-dark"}}
      {{#ionNavView}}
        {{> yield}}
      {{/ionNavView}}
    {{/ionBody}}
</template>

<template name="hello">
{{#contentFor "headerTitle"}}
  <h1 class="title">Hello</h1>
{{/contentFor}}

{{#ionView}}
  {{#ionContent}}
 	 Go to: <ul>
            <li>
              <a href="data">With data</a>
            </li>
            <li>
              <a href="nodata">Without data</a>
            </li>
          </ul>
  {{/ionContent}}
{{/ionView}}
</template>

<template name="post">
{{#contentFor "headerButtonLeft"}}
  {{>ionNavBackButton}}
{{/contentFor}}

{{#contentFor "headerTitle"}}
  <h1 class="title">Post</h1>
{{/contentFor}}

{{#ionView}}
  {{#ionContent}}
		<p>Post</p>
  {{/ionContent}}
{{/ionView}}
</template>

router.js

Router.configure({
  layoutTemplate: "layout"
});
Router.route("/data/", {
  data: function () {
    return "data";
  },
  action: function () {
   if (this.ready()) {
      this.render('post');
    } 
  }
});
Router.route("/nodata/", {
  action: function () {
   if (this.ready()) {
      this.render('post');
    } 
  }
});

Router.route("/", {
  action: function () {
   if (this.ready()) {
      this.render('hello');
    } 
  }
});