Answer by Chirag for Angular: conditional class with *ngClass

ngClass syntax:

[ngClass]="{'classname' : conditionFlag}"

You can use like this:

<ol class="breadcrumb"><li [ngClass]="{'active': step==='step1'}" (click)="step='step1'">Step1</li><li [ngClass]="{'active': step==='step2'}" (click)="step='step2'">Step2</li><li [ngClass]="{'active': step==='step3'}" (click)="step='step3'">Step3</li></ol>