Load content through Ajax in Angular Accordion component

import { Component, ViewChild } from '@angular/core';
import { Ajax } from '@syncfusion/ej2-base';
import { AccordionComponent} from '@syncfusion/ej2-angular-navigations';

@Component({
    selector: 'app-container',
    template: `
    <div id="acrdnContnet1" style="display:none">
        <ul style="margin : 0px;padding:0px 16px; list-style-type: none">
          <li>Testing</li>
          <li>Development</li>
        </ul>
    </div>
    <div id="acrdnContnet2" style="display:none">
      <ul style="margin : 0px;padding:0px 16px; list-style-type: none">
        <li>Mobile</li>
        <li>Web</li>
      </ul>
    </div>
    <ejs-accordion #acrdnInstance>
      <e-accordionitems>
        <e-accordionitem header='Department' content = '#acrdnContnet1'></e-accordionitem>
        <e-accordionitem header='Platform' content = '#acrdnContnet2'></e-accordionitem>
        <e-accordionitem header='Employee Details'></e-accordionitem>
      </e-accordionitems>
    </ejs-accordion>
        `
})

export class AppComponent {
    @ViewChild('acrdnInstance') acrdnInstance: AccordionComponent;
    public contentData: string;

    ngOnInit() {
    let ajax: Ajax = new Ajax('./ajax.html', 'GET', true);
    ajax.send().then();
    ajax.onSuccess = (data: string): void => {
       this.acrdnInstance.items[2].content = data;
       this.acrdnInstance.refresh();
    };
    }
}}

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AccordionModule } from '@syncfusion/ej2-angular-navigations';
import { AppComponent } from './app.component';

/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule, AccordionModule
    ],
    declarations: [AppComponent ],
    bootstrap: [AppComponent]
})
export class AppModule { }

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

enableProdMode();
platformBrowserDynamic().bootstrapModule(AppModule);

<div>
    <div class="comments-list">
        <div class="cont-list">
            <img src="http://js.syncfusion.com/demos/web/content/images/Employee/8.png" alt="contact" />
            <br>
            <div>
                <div class="time-panel">1 hr</div>
                <b class="headername">Erik Linden</b></div><br><br> London, one of the most popular tourist 
            destinations in the world for a reason. A cultural and historical hub, London has an excellent public 
            transportation system that allows visitors to see all the fantastic sights without spending a ton 
            of money on a rental car. London contains four World Heritage Sites.
            <div class="comments">
                <div class="c-list">Retweet</div>
                <div class="c-list">Reply</div>
                <div class="c-list">Share</div>
            </div>
        </div>       
    </div>
</div>
<style>
    .cont-list img {
        border-radius: 10px;
        float: left;
        height: 56px;
    }
    
    .comments {
        padding: 10px;
        color: #074B92;
        font-weight: 600;
        position: relative;
        top: 6px;
    }
    
    .cont-list {        
        padding-bottom: 9px;
    }
    
    .cont-list:last-child {
        border-bottom: none;
        padding-bottom: 10px;
    }
    
    .time-panel {
        float: right;
        color: #2382C3;
        margin-right: 10px;
        margin-top: 7px;
    }
    
    .headername {
        font-size: 16px;
        font-weight: 600;
        color: #074B92;
        position: relative;
        left: 9px;
    }
    
    .c-list {
        float: right;
        margin-top: -11px;
        padding-right: 12px;
    }
</style>