ng-gradient-button#track-mouse.ts

export class GradientButtonComponent {
  isGradientVisible = false;
  gradientTop: number;
  gradientLeft: number;

  constructor(public el: ElementRef<HTMLElement>) {}

  @HostListener('mouseenter')
  onMouseEnter() {
    this.isGradientVisible = true;
  }

  @HostListener('mouseleave')
  onMouseLeave() {
    this.isGradientVisible = false;
  }

  @HostListener('mousemove', ['$event'])
  onMouseMove(event: MouseEvent) {
    this.gradientLeft = event.pageX - this.el.nativeElement.offsetLeft;
    this.gradientTop = event.pageY - this.el.nativeElement.offsetTop;
  }
}