how to add alternate class name to object uisng angular 7 code example

Example 1: ngclass angular

<div [ngClass]="{ 
'green': number > 5,
  'red': number <= 5,
}" ></div>
//if the number is over 5, the class 'green' will be added to the div.
//if the number is below or equal 5, the class 'red' will be added to the div.

Example 2: ngclass

content_copy
      
      <some-element [ngClass]="'first second'">...</some-element>

<some-element [ngClass]="['first', 'second']">...</some-element>

<some-element [ngClass]="{'first': true, 'second': true, 'third': false}">...</some-element>

<some-element [ngClass]="stringExp|arrayExp|objExp">...</some-element>

<some-element [ngClass]="{'class1 class2 class3' : true}">...</some-element>