Add/Remove iron-selected class based on the paper-tab selection

Question

I have started learning Polymer & lit-element and was working on active & inactive status grid where i have used paper-tabs with iron-pages.

Question: When I switch between the paper-tabs, the iron-selected class is adding to the paper-tab links but not getting added to the iron-pages content.

How to make the iron-selected class work with the iron-pages content?

Any solution would be great!

constructor() {
    super();
    this.currentPage = 0;
}
render() {
return html `
<div class="card">
    <paper-tabs scrollable selected=${this.currentPage}>
        <paper-tab>Tab 1</paper-tab>
        <paper-tab>Tab 2</paper-tab>
        <paper-tab>Tab 3</paper-tab>
    </paper-tabs>
    <iron-pages selected=${this.currentPage}>
        <div>some story for tab 1</div>
        <div>some story for tab 2</div>
        <div>some story for tab 3</div>
    </iron-pages>
</div>
`;
}
}

Answer 1

Unlike Polymer, lit-html doesn't have a two way data binding mechanism so you have to take care of updating the currentPage property in the selected-changed event:

render() {
  return html`
    <div class="card">
      <paper-tabs scrollable
                  selected=${this.currentPage /* This is unidirectional */}
                  @selected-changed=${e => this.currentPage = e.detail.value}>
        <paper-tab>Tab 1</paper-tab>
        <paper-tab>Tab 2</paper-tab>
        <paper-tab>Tab 3</paper-tab>
      </paper-tabs>
      <iron-pages selected=${this.currentPage}>
        <div>some story for tab 1</div>
        <div>some story for tab 2</div>
        <div>some story for tab 3</div>
      </iron-pages>
    </div>
  `;
}