Angular Infinite Scroll

Inspired by ng-infinite-scroll directive for angular.

Angular Support

Supports Angular > 4
For Angular version <= 2.3.1, you can use npm i angular2-infinite-scroll (latest version is 0.3.42) - please notice the angular2-infinite-scroll package is deprecated

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Installation

npm install ngx-infinite-scroll --save

Supported API

Currently supported attributes:

• infiniteScrollDistance<number> - (optional, default: 2) - the bottom percentage point of the scroll nob relatively to the infinite-scroll container (i.e, 2 (2 * 10 = 20%) is event is triggered when 80% (100% - 20%) has been scrolled).
  if container.height is 900px, when the container is scrolled to or past the 720px, it will fire the scrolled event.
• infiniteScrollUpDistance<number> - (optional, default: 1.5) - should get a number
• infiniteScrollThrottle<number> - (optional, default: 150) - should get a number of milliseconds for throttle. The event will be triggered this many milliseconds after the user stops scrolling.
• infiniteScrollContainer<string|HTMLElement> - (optional, default: null) - should get a html element or css selector for a scrollable element; window or current element will be used if this attribute is empty.
• scrolled<function> - this will callback if the distance threshold has been reached on a scroll down.
• scrolledUp<function> - (event: InfiniteScrollEvent) - this will callback if the distance threshold has been reached on a scroll up.
• scrollWindow<boolean> - (optional, default: true) - listens to the window scroll instead of the actual element scroll. this allows to invoke a callback function in the scope of the element while listenning to the window scroll.
• immediateCheck<boolean> - (optional, default: false) - invokes the handler immediately to check if a scroll event has been already triggred when the page has been loaded (i.e. - when you refresh a page that has been scrolled).
• infiniteScrollDisabled<boolean> - (optional, default: false) - doesn't invoke the handler if set to true
• horizontal<boolean> - (optional, default: false) - sets the scroll to listen for horizontal events
• alwaysCallback<boolean> - (optional, default: false) - instructs the scroller to always trigger events
• fromRoot<boolean> - (optional, default: false) - if infiniteScrollContainer is set, this instructs the scroller to query the container selector from the root of the document object.

Behavior

By default, the directive listens to the window scroll event and invoked the callback.
To trigger the callback when the actual element is scrolled, these settings should be configured:

• [scrollWindow]="false"
• set an explict css "height" value to the element

DEMO

• Default Scroll By Window - plunkr
• Scroll On a "Modal" - plunkr

Usage

First, import the InfiniteScrollModule to your module:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { InfiniteScrollModule } from 'ngx-infinite-scroll';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { AppComponent } from './app';

@NgModule({
  imports:[ BrowserModule, InfiniteScrollModule ],
  declarations: [ AppComponent, ],
  bootstrap: [ AppComponent ]
})
export class AppModule { }

platformBrowserDynamic().bootstrapModule(AppModule);

In this example, the onScroll callback will be invoked when the window is scrolled down:

import { Component } from '@angular/core';

@Component({
	selector: 'app',
	template: `
		<div class="search-results"
		    infiniteScroll
		    [infiniteScrollDistance]="2"
		    [infiniteScrollThrottle]="50"
		    (scrolled)="onScroll()">
		</div>
	`
})
export class AppComponent {
	onScroll () {
	    console.log('scrolled!!')
	}
}

in this example, whenever the "search-results" is scrolled, the callback will be invoked:

import { Component } from '@angular/core';

@Component({
	selector: 'app',
	styles: [
		`.search-results {
			height: 20rem;
			overflow: scroll;
		}`
	],
	template: `
		<div class="search-results"
		    infiniteScroll
		    [infiniteScrollDistance]="2"
		    [infiniteScrollThrottle]="50"
		    (scrolled)="onScroll()"
		    [scrollWindow]="false">
		</div>
	`
})
export class AppComponent {
	onScroll () {
	    console.log('scrolled!!')
	}
}

In this example, the onScrollDown callback will be invoked when the window is scrolled down and the onScrollUp callback will be invoked when the window is scrolled up:

import { Component } from '@angular/core';
import { InfiniteScroll } from 'ngx-infinite-scroll';

@Component({
	selector: 'app',
	directives: [ InfiniteScroll ],
	template: `
		<div class="search-results"
		    infiniteScroll
		    [infiniteScrollDistance]="2"
		    [infiniteScrollUpDistance]="1.5"
		    [infiniteScrollThrottle]="50"
		    (scrolled)="onScrollDown()"
		    (scrolledUp)="onScrollUp()">
		</div>
	`
})
export class AppComponent {
	onScrollDown () {
	    console.log('scrolled down!!')
	}

	onScrollUp () {
    	console.log('scrolled up!!')
    }
}

In this example, the infiniteScrollContainer attribute is used to point directive to the scrollable container using a css selector. fromRoot is used to determine whether the scroll container has to be searched within the whole document ([fromRoot]="true") or just inside the infiniteScroll directive ([fromRoot]="false", default option).

import { Component } from '@angular/core';

@Component({
	selector: 'app',
	styles: [
		`.main-panel {
			height: 100px;
			overflow-y: scroll;
		}`
	],
	template: `
		<div class="main-panel">
			<div infiniteScroll
			    [infiniteScrollDistance]="2"
			    [infiniteScrollThrottle]="50"
			    [infiniteScrollContainer]="selector"
			    [fromRoot]="true"
			    (scrolled)="onScroll()">
			</div>
		</div>
	`
})
export class AppComponent {
	selector: string = '.main-panel';
	
	onScroll () {
	    console.log('scrolled!!')
	}
}

It is also possible to use infiniteScrollContainer without additional variable by using single quotes inside double quotes:

[infiniteScrollContainer]="'.main-panel'"

Showcase Examples

• Echoes Player - Developed with Angular, angular-cli and ngrx (github repo for echoes player)

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