Lazy image loader for Angular ≥ v2
About 150 loc and no dependencies (except for angular and rxjs of course)
Demo: http://tjoskar.github.io/ng-lazyload-image/
The browser you targeting need to have support of WeakMap and String.prototype.includes. If you need to support an older browser (like IE) you will need to include polyfill for WeakMap and String.prototype.includes (see https://github.com/zloirock/core-js for example).
$ npm install ng-lazyload-image --save
And then include it in your module (see app.module.ts):
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { LazyLoadImageModule } from 'ng-lazyload-image';
import { AppComponent } from './app.component';
@NgModule({
declarations: [ AppComponent ],
imports: [ BrowserModule, LazyLoadImageModule ],
bootstrap: [ AppComponent ]
})
export class MyAppModule {}import { Component } from '@angular/core';
@Component({
selector: 'image',
template: `
<img [defaultImage]="defaultImage" [lazyLoad]="image" [offset]="offset">
`
})
class ImageComponent {
defaultImage = 'https://www.placecage.com/1000/1000';
image = 'https://images.unsplash.com/photo-1443890923422-7819ed4101c0?fm=jpg';
offset = 100;
}It also supports background images, by using backgroundImage:
@Component({
selector: 'image',
template: `
<div [defaultImage]="defaultImage" [lazyLoad]="image" [offset]="offset"></div>
<!--
After it has been loaded the div will transform into:
<div class="ng-lazyloaded" style="background-image: url('https://images.unsplash.com/photo-1443890923422-7819ed4101c0?fm=jpg');"></div>
-->
`
})
class ImageComponent {
defaultImage = 'https://www.placecage.com/1000/1000';
image = 'https://images.unsplash.com/photo-1443890923422-7819ed4101c0?fm=jpg';
offset = 100;
}You can (from 3.3.0) load image async or change the url on the fly, eg.
<img [lazyLoad]="image$ | async">If you are using Ionic 2 you may need to include your own scroll observable or change the scroll target.
@Component({
selector: 'page-image',
template: `
<ion-content #container padding>
<img [defaultImage]="https://www.placecage.com/1000/1000" [lazyLoad]="lazyLoadImage" [scrollObservable]="container.ionScroll" />
</ion-content>
`
})
export class AboutPage {
lazyLoadImage = 'https://hd.unsplash.com/photo-1431400445088-1750c997c6b5';
}See example folder for more usages.
Q How can I manually trigger the loading of images?
A See: tjoskar#197
Q Does this library work with ionic or some other wrapper for Angular?
A Yes, but ionic and some other library wraps the whole document inside an other div so you might need to create your own scroll listener. https://github.com/tjoskar/ng-lazyload-image/issues?utf8=%E2%9C%93&q=is%3Aissue+Ionic
Type: string
Example: https://images.unsplash.com/photo-1443890923422-7819ed4101c0?fm=jpg
The image to be lazy loaded. This image will replace the default image (defaultImage).
Type: string
Example: https://www.placecage.com/1000/1000
Path to default image. This image will be loaded right away.
You can also use src attribute for img tag to define default image:
<img src="https://www.placecage.com/1000/1000" [lazyLoad]="lazyLoadImage" />
or background-image property for non-image tags:
<div style="background-image: url('https://www.placecage.com/1000/1000');" [lazyLoad]="lazyLoadImage"></div>
Type: string
Example: https://i.imgur.com/XkU4Ajf.png
An image to be loaded if failing to load lazyLoad. Will load the default image (defaultImage) if absent.
Type: number
Example: 100
Default: 0
Number of px a image should be loaded before it is in view port
Type: Element
Example: document.getElementById('my-scroll-container')
Default: window
You will need to set this property if you are using a scroll container and do not propagate the scroll event to window.
Type: Observable
Example: Observable.fromEvent(myScrollContainer, 'scroll')
You can pass your own observable if you need more control over the flow. Can be useful if integrating with other frameworks like ionic.
Type: Function: (success: boolean) => void
Example: <img [lazyLoad]="lazyLoadImage" (onLoad)="myCallbackFunction($event)">
You can pass a callback function, which will be called when the image is loaded.
See the contributing guide