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https://github.com/dockyard/ember-in-viewport
Detect if an Ember View or Component is in the viewport @ 60FPS
https://github.com/dockyard/ember-in-viewport
ember intersectionobserver viewport
Last synced: 22 days ago
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Detect if an Ember View or Component is in the viewport @ 60FPS
- Host: GitHub
- URL: https://github.com/dockyard/ember-in-viewport
- Owner: DockYard
- License: mit
- Created: 2015-04-13T13:51:50.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2024-05-21T16:01:40.000Z (6 months ago)
- Last Synced: 2024-10-01T08:42:41.263Z (about 1 month ago)
- Topics: ember, intersectionobserver, viewport
- Language: JavaScript
- Homepage:
- Size: 4.85 MB
- Stars: 245
- Watchers: 11
- Forks: 91
- Open Issues: 28
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE.md
- Code of conduct: CODE_OF_CONDUCT.md
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README
# ember-in-viewport
*Detect if an Ember View or Component is in the viewport @ 60FPS*
**[ember-in-viewport is built and maintained by DockYard, contact us for expert Ember.js consulting](https://dockyard.com/ember-consulting)**.
[Read the blogpost](https://medium.com/delightful-ui-for-ember-apps/creating-an-ember-cli-addon-detecting-ember-js-components-entering-or-leaving-the-viewport-7d95ceb4f5ed)
[](http://badge.fury.io/js/ember-in-viewport)
[](https://github.com/DockYard/ember-in-viewport/actions/workflows/ci.yml?query=branch%3Amaster)
[](http://emberobserver.com/addons/ember-in-viewport)
This Ember addon adds a simple, highly performant Service or modifier to your app. This library will allow you to check if a `Component` or DOM element has entered the browser's viewport. By default, this uses the `IntersectionObserver` API if it detects it the DOM element is in your user's browser – failing which, it falls back to using `requestAnimationFrame`, then if not available, the Ember run loop and event listeners.
We utilize pooling techniques to reuse Intersection Observers and rAF observers in order to make your app as performant as possible and do as little works as possible.
## Demo or examples
- Lazy loading responsive images (see `dummy-artwork` for an example artwork component). Visit `http://localhost:4200/infinity-modifier` to see it in action
- Dummy app (`ember serve`): https://github.com/DockYard/ember-in-viewport/tree/master/tests/dummy
- Use with Ember [Modifiers](#modifiers) and [@ember/render-modifiers](https://github.com/emberjs/ember-render-modifiers)
- Use with [Native Classes](#classes)
- [ember-infinity](https://github.com/ember-infinity/ember-infinity)
- [ember-light-table](https://github.com/offirgolan/ember-light-table)
- Tracking advertisement impressions
- Occlusion culling
# Table of Contents
- [Installation](#installation)
* [Usage](#usage)
+ [Configuration](#configuration)
+ [Global options](#global-options)
+ [Modifiers](#modifiers)
* [**IntersectionObserver**'s Browser Support](#intersectionobservers-browser-supportscrollableArea)
+ [Out of the box](#out-of-the-box)
* [Running](#running)
* [Running Tests](#running-tests)
* [Building](#building)
* [Legal](#legal)
# Installation
```
ember install ember-in-viewport
```
## Usage
Usage is simple. First, inject the service to your component and start "watching" DOM elements.
```js
import Component from '@glimmer/component';
import { action } from '@ember/object';
import { inject as service } from '@ember/service';
export default class MyClass extends Component {
@service inViewport
@action
setupInViewport() {
const loader = document.getElementById('loader');
const viewportTolerance = { bottom: 200 };
const { onEnter, _onExit } = this.inViewport.watchElement(loader, { viewportTolerance });
// pass the bound method to `onEnter` or `onExit`
onEnter(this.didEnterViewport.bind(this));
}
didEnterViewport() {
// do some other stuff
this.infinityLoad();
}
willDestroy() {
// need to manage cache yourself
const loader = document.getElementById('loader');
this.inViewport.stopWatching(loader);
super.willDestroy(...arguments);
}
}
```
```hbs
-
...
```
You can also use [`Modifiers`](#modifiers) as well. Using modifiers cleans up the boilerplate needed and is shown in a later example.
### Configuration
To use with the service based approach, simply pass in the options to `watchElement` as the second argument.
```js
import Component from '@glimmer/component';
import { inject as service } from '@ember/service';
export default class MyClass extends Component {
@service inViewport
@action
setupInViewport() {
const loader = document.getElementById('loader');
const { onEnter, _onExit } = this.inViewport.watchElement(
loader,
{
viewportTolerance: { bottom: 200 },
intersectionThreshold: 0.25,
scrollableArea: '#scrollable-area'
}
);
}
}
```
### Global options
You can set application wide defaults for `ember-in-viewport` in your app (they are still manually overridable inside of a Component). To set new defaults, just add a config object to `config/environment.js`, like so:
```js
module.exports = function(environment) {
var ENV = {
// ...
viewportConfig: {
viewportUseRAF : true,
viewportSpy : false,
viewportListeners : [],
intersectionThreshold : 0,
scrollableArea : null,
viewportTolerance: {
top : 0,
left : 0,
bottom : 0,
right : 0
}
}
};
};
// Note if you want to disable right and left in-viewport triggers, set these values to `Infinity`.
```
### Modifiers
Using with [Modifiers](https://blog.emberjs.com/2019/03/06/coming-soon-in-ember-octane-part-4.html) is easy.
You can either use our built in modifier `{{in-viewport}}` or a more verbose, but potentially more flexible generic modifier. Let's start with the former.
1. Use `{{in-viewport}}` modifier on target element
2. Ensure you have a callbacks in context for enter and/or exit
3. `options` are optional - see [Advanced usage (options)](#advanced-usage-options)
```hbs
-
-
List sentinel
```
This modifier is useful for a variety of scenarios where you need to watch a sentinel. With template only components, functionality like this is even more important! If you have logic that currently uses the `did-insert` modifier to start watching an element, try this one out!
If you need more than our built in modifier...
1. Install [@ember/render-modifiers](https://github.com/emberjs/ember-render-modifiers)
2. Use the `did-insert` hook inside a component
3. Wire up the component like so
Note - This is in lieu of a `did-enter-viewport` modifier, which we plan on adding in the future. Compared to the solution below, `did-enter-viewport` won't need a container (`this`) passed to it. But for now, to start using modifiers, this is the easy path.
```js
import Component from '@glimmer/component';
import { action } from '@ember/object';
import { inject as service } from '@ember/service';
export default class MyClass extends Component {
@service inViewport
@action
setupInViewport() {
const loader = document.getElementById('loader');
const viewportTolerance = { bottom: 200 };
const { onEnter, _onExit } = this.inViewport.watchElement(loader, { viewportTolerance });
onEnter(this.didEnterViewport.bind(this));
}
didEnterViewport() {
// do some other stuff
this.infinityLoad();
}
willDestroy() {
// need to manage cache yourself
const loader = document.getElementById('loader');
this.inViewport.stopWatching(loader);
super.willDestroy(...arguments);
}
}
```
```hbs
{{yield}}
```
Options as the second argument to `inViewport.watchElement` include:
- `intersectionThreshold: decimal or array`
Default: 0
A single number or array of numbers between 0.0 and 1.0. A value of 0.0 means the target will be visible when the first pixel enters the viewport. A value of 1.0 means the entire target must be visible to fire the didEnterViewport hook.
Similarily, [0, .25, .5, .75, 1] will fire didEnterViewport every 25% of the target that is visible.
(https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API#Thresholds)
Some notes:
- If the target is offscreen, you will get a notification via `didExitViewport` that the target is initially offscreen. Similarily, this is possible to notify if onscreen when your site loads.
- If intersectionThreshold is set to anything greater than 0, you will not see `didExitViewport` hook fired due to our use of the `isIntersecting` property. See last comment here: https://bugs.chromium.org/p/chromium/issues/detail?id=713819 for purpose of `isIntersecting`
- To get around the above issue and have `didExitViewport` fire, set your `intersectionThreshold` to `[0, 1.0]`. When set to just `1.0`, when the element is 99% visible and still has isIntersecting as true, when the element leaves the viewport, the element isn't applicable to the observer anymore, so the callback isn't called again.
- If your intersectionThreshold is set to 0 you will get notified if the target `didEnterViewport` and `didExitViewport` at the appropriate time.
- `scrollableArea: string | HTMLElement`
Default: null
A CSS selector for the scrollable area. e.g. `".my-list"`
- `viewportSpy: boolean`
Default: `false`
`viewportSpy: true` is often useful when you have "infinite lists" that need to keep loading more data.
`viewportSpy: false` is often useful for one time loading of artwork, metrics, etc when the come into the viewport.
If you support IE11 and detect and run logic `onExit`, then it is necessary to have this `true` to that the requestAnimationFrame watching your sentinel is not torn down.
When `true`, the library will continually watch the `Component` and re-fire hooks whenever it enters or leaves the viewport. Because this is expensive, this behaviour is opt-in. When false, the intersection observer will only watch the `Component` until it enters the viewport once, and then it unbinds listeners. This reduces the load on the Ember run loop and your application.
NOTE: If using IntersectionObserver (default), viewportSpy wont put too much of a tax on your application. However, for browsers (Safari < 12.1) that don't currently support IntersectionObserver, we fallback to rAF. Depending on your use case, the default of `false` may be acceptable.
- `viewportTolerance: object`
Default: `{ top: 0, left: 0, bottom: 0, right: 0 }`
This option determines how accurately the `Component` needs to be within the viewport for it to be considered as entered. Add bottom margin to preemptively trigger didEnterViewport.
For IntersectionObserver, this property interpolates to [rootMargin](https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver/rootMargin).
For rAF, this property will use `bottom` tolerance and measure against the height of the container to determine when to trigger didEnterViewport.
Also, if your sentinel (the watched element) is a zero-height element, ensure that the sentinel actually is able to enter the viewport.
## [**IntersectionObserver**'s Browser Support](https://platform-status.mozilla.org/)
### Out of the box
Chrome
51 [1]
Firefox (Gecko)
55 [2]
MS Edge
15
Internet Explorer
Not supported
Opera [1]
38
Safari
Safari Technology Preview
Chrome for Android
59
Android Browser
56
Opera Mobile
37
* [1] [Reportedly available](https://www.chromestatus.com/features/5695342691483648), it didn't trigger the events on initial load and lacks `isIntersecting` until later versions.
* [2] This feature was implemented in Gecko 53.0 (Firefox 53.0 / Thunderbird 53.0 / SeaMonkey 2.50) behind the preference `dom.IntersectionObserver.enabled`.
## Running
* `ember serve`
* Visit your app at http://localhost:4200.
## Running Tests
* `ember test`
* `ember test --serve`
## Building
* `ember build`
For more information on using ember-cli, visit [http://www.ember-cli.com/](http://www.ember-cli.com/).
## Legal
[DockYard](http://dockyard.com/ember-consulting), Inc © 2015
[@dockyard](http://twitter.com/dockyard)
[Licensed under the MIT license](http://www.opensource.org/licenses/mit-license.php)
## Contributors
We're grateful to these wonderful contributors who've contributed to `ember-in-viewport`:
[//]: contributor-faces
[//]: contributor-faces