Angular Infinite Scroll

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

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'"