main.ts

const FirstChild = {
  template: "<div>Hi I'm the first child</div>"
};

const SecondChild = {
  template: "<div>Hi I'm the second child</div>"
};

const ParentComponent = {
  template: `<div>
      Hi I'm the parent, I will stay here
      <router-view></router-view>
      <router-link to="/parent/first-child">First Child</router-link>
      <router-link to="/parent/second-child">Second Child</router-link>
    </div>
  `
};

const ParentRoute = {
  path: "/parent",
  name: "parent",
  component: ParentComponent,
  children: [
    {
      path: "first-child",
      component: FirstChild
    },
    {
      path: "second-child",
      component: SecondChild
    }
  ]
};

const routes = [
  ParentRoute
];