Angular: conditional class with *ngClass

Question

What is wrong with my Angular code? I am getting the following error:

Cannot read property 'remove' of undefined at BrowserDomAdapter.removeClass

<ol>
  <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>

Answer 1

Angular version 2+ provides several ways to add classes conditionally:

Type one

    [class.my_class] = "step === 'step1'"

Type two

    [ngClass]="{'my_class': step === 'step1'}"

and multiple options:

    [ngClass]="{'my_class': step === 'step1', 'my_class2' : step === 'step2' }"

Type three

    [ngClass]="{1 : 'my_class1', 2 : 'my_class2', 3 : 'my_class4'}[step]"

Type four

    [ngClass]="step == 'step1' ? 'my_class1' : 'my_class2'"

You can find these examples on the the documentation page.