If you plan using background images a lot throughout your project you may find it useful to create a really simple custom pipe that will create the url for you.
import { Pipe, PipeTransform } from '@angular/core';
@Pipe({
name: 'asUrl'
})
export class BackgroundUrlPipe implements PipeTransform {
transform(value: string): string {
return `url(./images/${value})`
}
}
Then you can add background images without all the string concatenation.
<div [ngStyle]="{ background: trls.img | asUrl }"></div>