javascript - 如何仅在鼠标滚轮滚动时触发

Question

我正在尝试用鼠标滚轮滚动来执行一些操作。我希望无论你滚动滚轮的速度有多快或多少次，它都算作“一”。现在，如果您快速滚动，它会计数更多次。

https://stackblitz.com/edit/angular-yttk3y

Answer 1

有一个计时器来限制滚动一定的持续时间并保留滚动方向以检测滚动方向的变化。

import { Directive, HostListener } from '@angular/core';
import { timer } from 'rxjs';
@Directive({
  selector: '[appMouseScroll]'
})
export class MouseScrollDirective {
  Ttimer;
  isMouseWheelInRogress;
  scrollUp;

  @HostListener('wheel', ['$event']) onMouseScroll(e) {

    if (!this.isMouseWheelInRogress || (!this.scrollUp && e.deltaY < 0 || this.scrollUp && e.deltaY > 0)) {
      if (this.Ttimer) {
        this.Ttimer.unsubscribe();
      }
      this.Ttimer = timer(500).subscribe(() => {
        this.isMouseWheelInRogress = false;
      });

      if (e.deltaY < 0) {
        this.scrollUp = true;
        console.log('scrolling up');
      } else if (e.deltaY > 0) {
        this.scrollUp = false;
        console.log('scrolling down');
      }
    }
    this.isMouseWheelInRogress = true;
  }
}