ember-router-scroll

ember-router-scroll

Scroll to page top on transition, like a non-SPA website. An alternative scroll behavior for Ember applications.

Installation

ember install ember-router-scroll

Options

If you need to scroll to the top of an area that generates a vertical scroll bar, you can specify the id of an element of the scrollable area. Default is window for using the scroll position of the whole viewport. You can pass an options object in your application's config/environment.js file.

ENV['routerScroll'] = {
  scrollElement: '#mainScrollElement'
};

If you want to scroll to a target element on the page, you can specify the id or class of the element on the page.  This is particularly useful if instead of scrolling to the top of the window, you want to scroll to the top of the main content area (that does not generate a vertical scrollbar).

ENV['routerScroll'] = {
  targetElement: '#main-target-element' // or .main-target-element
};

Moreover, if your route breaks up render into multiple phases, you may need to delay scrollTop functionality until after the First Meaningful Paint using `delayScrollTop: true` in your config.  `delayScrollTop` defaults to `false`.

```javascript
ENV['routerScroll'] = {
  delayScrollTop: true
};

A working example

See demo made by Jon Chua.

A visual demo

Before

Notice that the in the full purple page, the user is sent to the middle of the page.

After

Notice that the in the full purple page, the user is sent to the top of the page.

Why Use it?

Ember expects an application to be rendered with nested views. The default behavior is for the scroll position to be preserved on every transition. However, not all Ember applications use nested views. For these applications, a user would expect to see the top of the page on most transitions.

In addition to scrolling to the top of the page on most transitions, a user would expect the scroll position to be preserved when using the back or forward browser buttons.

ember-router-scroll makes your single page application feel more like a regular website.

Installation & Usage

1. Install addon

ember install ember-router-scroll

1. Import ember-router-scroll

In your app/router.js file, import the mixin:

import RouterScroll from 'ember-router-scroll';

And add RouterScroll as an extension to your Router object:

const Router = Ember.Router.extend(RouterScroll, {});

1. Update your app's locationType

Edit config/environment.js and change locationType. Also add historySupportMiddleware: true, to get live-reload working in nested routes. (See Issue #21)

locationType: 'router-scroll',
historySupportMiddleware: true,

This location type inherits from Ember's HistoryLocation.

1. If using old style QUnit tests. If tests based on RFC, you can ignore this. In your router and controller tests, add 'service:router-scroll' as a dependency in the needs: [] block:

//{your-app}}/tests/unit/routes/{{your-route}}.js
needs:[ 'service:router-scroll' ],

Issues with nested routes

Before:

Notice the unwanted scroll to top in this case.

After:

Adding a query parameter or controller property fixes this issue.

preserveScrollPosition with queryParams

In certain cases, you might want to have certain routes preserve scroll position when coming from a specific location. For example, inside your application, there is a way to get to a route where the user expects scroll position to be preserved (such as a tab section).

1. Add query param in controller

Add preserveScrollPosition as a queryParam in the controller for the route that needs to preserve the scroll position.

Example:

import Controller from '@ember/controller';

export default Controller.extend({
  queryParams: [
    'preserveScrollPosition',
  ],
});

1. Pass in query param

Next, in the place where a transition is triggered, pass in preserveScrollPosition=true. For example

{{link-to "About Tab" 'tab.about' (query-params preserveScrollPosition=true) }}

preserveScrollPosition wiith a controller property

In other cases, you may have certain routes that always preserve scroll position, or routes where the controller can decide when to preserve scroll position. For instance, you may have some nested routes that have true nested UI where preserving scroll position is expected. Or you want a particular route to start off with the default scroll-to-top behavior but then preserve scroll position when query params change in reponse to user interaction. Using a conroller property also allows the use of preserveScrollPosition without adding this to the query params.

1. Add query param to controller

Add preserveScrollPosition as a controller property for the route that needs to preserve the scroll position. In this example we have preserveScrollPosition initially set to false so that we get our normal scroll-to-top behavior when the route loads. Later on, when an action triggers a change to the filter query param, we also set preserveScrollPosition to true so that this user interaction does not trigger the scroll-to-top behavior.

Example:

import Controller from '@ember/controller';

export default Controller.extend({
  queryParams: ['filter'],

  preserveScrollPosition: false,

  actions: {
    changeFilter(filter) {
      this.set('preserveScrollPosition', true);
      this.set('filter', filter);
    }
  }
});

1. Reset preserveScrollPosition if necessary

If your controller is changing the preserveScrollPosition property, you'll probably need to reset preserveScrollPosition back to the default behavior whenever the controller is reset. This is not necceary on routes where preserveScrollPosition is always set to true.

import Router from '@ember/routing/route';

export default Route.extend({
  resetController(controller) {
    controller.set('preserveScrollPosition', false);
  }
});

Running Tests

• npm test (Runs ember try:testall to test your addon against multiple Ember versions)
• ember test
• ember test --server