Getter for multiple classes for ngClass

// Getter to return classes including backgroundColor
public get classes(): { [key: string]: boolean } {
    const classList: { [key: string]: boolean } = {
      loading: this.isLoading,
      wide: this.isWide,
    };

    if (this.backgroundColor) {
      classList[this.backgroundColor] = true;
    }

    return classList;
}

<div [ngClass]="classes"></div>