Add multiple classes in ngClass using string concatenation

Question

I am trying to add multiple classes in ngClass, where one of the classes is a concatenation of a literal string and a variable. This is what I need, but I got a syntax error:

<div [ngClass]="[{'w-' + percentage}, {'finished': true}]"></div>

Where is the error in this expression?

Answer 1

<div [ngClass]="'w-' + percentage" [class.finished]="true/false"></div>

or if class finished is not connected to any variable then:

<div class="finished" [ngClass]="'w-' + percentage"></div>

Answer 2

Write like this, It will resolve your problem.

<div [ngClass]="{'w-' + percentage: true, 'finished': true}"></div>