iron-lazy-pages | Vaadin

Lazy-load content and lazy-register pages to reduce the first load time


Published on Build Status

<iron-pages> with lazy-loading functionality.

Lazy-loading pages

Big applications have a lot of pages. On first load, loading all page elements is undesirable. Most of the pages are unused for the current user. To solve these performance issues, lazy-loading provides an easy-to-use solution.

Lazy-loading means that all elements of your page are loaded when the user opens the respective page. E.g. when your user visits, all elements on the about page are fetched and loaded.


<iron-lazy-pages attr-for-selected="data-route" selected="{{route}}">
  <x-foo data-route="foo" data-path="demo/x-foo.html"></x-foo>
  <x-bar data-route="bar" data-path="demo/x-bar.html"></x-bar>
  <section data-route="baz">
    Inline element baz.

In the above example, whenever the user routes to, the elements defined in foo/foo.html are fetched from the server and loaded by Polymer.

Consequently whenever the selected value changes from foo to bar, the page foo will be hidden.

Fetching is only performed once, e.g. switching from foo to bar to foo will fetch foo once and show foo twice.

<dom-if> support

You can also add <dom-if> as a route to enable restamping:

  <template is="dom-if" data-route="foo" restamp>
    Leaving this tab and coming back will loose input value due to restamp<br/>
    <input type="text"/>
  <template is="dom-if" data-route="bar">
    Leaving this tab and coming back will keep input value<br/>
    <input type="text"/>


Link to this version
ImportedReleased 16 June 2018BSD 3-clause "New" or "Revised" License
Framework Support
Polymer 3.0+
Also supported:
Polymer 1 (1.5.1)Polymer 2 (2.1.1)
Browser Independent
Install with
npm install iron-lazy-pages"@3.0.2"
Run the above npm command in your project folder. If you have any issues installing, please contact the author.
Release notes - Version 3.0.2


  • @polymer/polymer#^3.0.0
  • @polymer/iron-selector#^3.0.0-pre.18