Load on-demand in Angular Chat UI component

21 Jan 20253 minutes to read

You can use the loadOnDemand property to load messages dynamically when the scroll reaches the top of the message list improving performance and reducing load times, particularly in long conversations. This ensures a smooth user experience by only fetching messages as needed rather than loading the entire conversation at once.

app.component.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { ChatUIModule } from '@syncfusion/ej2-angular-interactive-chat';
import { UserModel, MessageModel } from '@syncfusion/ej2-interactive-chat';
import { Component } from '@angular/core';


@Component({
    imports: [ FormsModule, ReactiveFormsModule, ChatUIModule ],
    standalone: true,
    selector: 'app-root',
    templateUrl: './app.component.html'
})

export class AppComponent {
    public currentUserModel: UserModel = { user: 'Albert', id: 'user1' };
    public michaleUserModel: UserModel = { user: 'Michale Suyama', id: 'user2' };
    public chatMessages: MessageModel[] = [];
    public ngOnInit(): void {
        for (let i = 1; i <= 150; i++) {
            this.chatMessages.push({
                text: i % 2 === 0 
                    ? `Message ${i} from Michale` 
                    : `Message ${i} from Albert`,
                author: i % 2 === 0 ? this.michaleUserModel : this.currentUserModel
            });
        }
    }
}

main.ts

import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import 'zone.js';
bootstrapApplication(AppComponent).catch((err) => console.error(err));

app.component.html

<div id="chatui" ejs-chatui [user]="currentUserModel" [loadOnDemand]="true" [messages]="chatMessages"></div>