the correct syntax for adding an ngclass property binding to current class in angular code example

Example 1: Angular 8 ngClass If

[ngClass]="{'my-class': step=='step1'}"

Example 2: ng class multiple class names

<!-- notice expression1 used twice -->
<div ng-class="{class1 : expression1, class2 : expression1}">
    Hello World!
</div>

Example 3: Angular 8 ngClass If

[ngClass]="{1:'my-class1',2:'my-class2',3:'my-class4'}[step]"

Example 4: angular bind to class or ngClass

<div [ngClass]="{'extra-sparkle': isDelightful}">