ngx-infinite-scroll

What is ngx-infinite-scroll?

The ngx-infinite-scroll package is an Angular directive that allows you to implement infinite scrolling in your Angular applications. It provides a simple way to load more data as the user scrolls down the page, enhancing the user experience by avoiding the need for pagination.

What are ngx-infinite-scroll's main functionalities?

Basic Infinite Scroll

This feature allows you to implement basic infinite scrolling. The `infiniteScroll` directive is added to a container, and the `scrolled` and `scrolledUp` events are used to load more data when the user scrolls down or up, respectively.

<template>
  <div infiniteScroll
       [infiniteScrollDistance]="2"
       [infiniteScrollUpDistance]="1.5"
       [infiniteScrollThrottle]="300"
       (scrolled)="onScrollDown()"
       (scrolledUp)="onScrollUp()">
    <!-- content here -->
  </div>
</template>

<script>
import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  onScrollDown() {
    console.log('scrolled down!!');
    // Load more data here
  }

  onScrollUp() {
    console.log('scrolled up!!');
    // Load more data here
  }
}
</script>

Custom Scroll Distance

This feature allows you to customize the scroll distance at which the `scrolled` event is triggered. In this example, the `infiniteScrollDistance` is set to 1, meaning the event will be triggered when the user scrolls to the bottom of the container.

<template>
  <div infiniteScroll
       [infiniteScrollDistance]="1"
       (scrolled)="onScroll()">
    <!-- content here -->
  </div>
</template>

<script>
import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  onScroll() {
    console.log('scrolled!!');
    // Load more data here
  }
}
</script>

Throttle Scroll Events

This feature allows you to throttle the scroll events to improve performance. The `infiniteScrollThrottle` input is used to specify the delay in milliseconds between successive scroll events. In this example, the scroll events are throttled to 200 milliseconds.

<template>
  <div infiniteScroll
       [infiniteScrollThrottle]="200"
       (scrolled)="onScroll()">
    <!-- content here -->
  </div>
</template>

<script>
import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  onScroll() {
    console.log('scrolled!!');
    // Load more data here
  }
}
</script>

Other packages similar to ngx-infinite-scroll

ngx-scroll-event

The ngx-scroll-event package provides a simple way to handle scroll events in Angular applications. It allows you to detect when the user scrolls to the top, bottom, or a specific position of a container. Compared to ngx-infinite-scroll, ngx-scroll-event offers more granular control over scroll events but does not provide built-in infinite scrolling functionality.

ngx-virtual-scroller

The ngx-virtual-scroller package is an Angular component that provides virtual scrolling for large lists. It renders only the visible items in the list, improving performance for large datasets. While ngx-virtual-scroller focuses on optimizing rendering performance, ngx-infinite-scroll is more about loading additional data as the user scrolls.

angular2-infinite-scroll

The angular2-infinite-scroll package is another Angular directive for implementing infinite scrolling. It offers similar functionality to ngx-infinite-scroll, allowing you to load more data as the user scrolls. However, ngx-infinite-scroll is more actively maintained and has better documentation.

README

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Angular Infinite Scroll

versions now follow Angular's version to easily reflect compatibility.
Meaning, for Angular 10, use ngx-infinite-scroll @ ^10.0.0

Angular - Older Versions Support

Starting Angular 6 and Above - ngx-infinite-scroll@THE_VERSION.0.0
For Angular 4 and Angular = ^5.5.6 - use version ngx-infinite-scroll@0.8.4
For Angular 5.x with rxjs =<5.5.2 - use version ngx-infinite-scroll@0.8.3
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

Properties

@Input()	Type	Required	Default	Description
infiniteScrollDistance	number	optional	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	1.5	should get a number
infiniteScrollThrottle	number	optional	150	should get a number of milliseconds for throttle. The event will be triggered this many milliseconds after the user stops scrolling.
scrollWindow	boolean	optional	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	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	false	doesn't invoke the handler if set to true
horizontal	boolean	optional	false	sets the scroll to listen for horizontal events
alwaysCallback	boolean	optional	false	instructs the scroller to always trigger events
infiniteScrollContainer	string / HTMLElement	optional	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.
fromRoot	boolean	optional	false	if infiniteScrollContainer is set, this instructs the scroller to query the container selector from the root of the document object.

Events

@Output()	Type	Event Type	Required	Description
scrolled	EventEmitter	IInfiniteScrollEvent	optional	this will callback if the distance threshold has been reached on a scroll down.
scrolledUp	EventEmitter	IInfiniteScrollEvent	optional	this will callback if the distance threshold has been reached on a scroll up.

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

Try the Demo in StackBlitz

Usage

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

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

@Component({
  selector: 'app',
  template: `
    <div
      class="search-results"
      infiniteScroll
      [infiniteScrollDistance]="2"
      [infiniteScrollThrottle]="50"
      (scrolled)="onScroll()"
    ></div>
  `,
  imports: [InfiniteScrollDirective]
})
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';
import { InfiniteScrollDirective } from 'ngx-infinite-scroll';

@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>
  `,
  imports: [InfiniteScrollDirective]
})
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';
import { InfiniteScrollDirective } from 'ngx-infinite-scroll';

@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>
  `,
  imports: [InfiniteScrollDirective]
})
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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