Vanilla JS slideup slidedown slidetoggle

slide.js

  let fadeOut = (target, duration=500) => {
    target.style.transitionProperty = 'opacity';
    target.style.transitionDuration = duration + 'ms';
    target.style.opacity = 0;
    window.setTimeout( () => {
      target.style.display = 'none';
      target.style.removeProperty('opacity');
      target.style.removeProperty('transition-duration');
      target.style.removeProperty('transition-property');
      //alert("!");
    }, duration);
  }
  
  let fadeIn = (target, duration=500) => {
    target.style.opacity = 0;
    target.style.removeProperty('display');
    let display = window.getComputedStyle(target).display;

    if (display === 'none')
      display = 'block';

    target.style.display = display;
      target.style.transitionProperty = "opacity";
      target.style.transitionDuration = duration + 'ms';
    window.setTimeout(() => {
      target.style.opacity = 1;
      window.setTimeout( () => {
        target.style.removeProperty('opacity');
        target.style.removeProperty('transition-duration');
        target.style.removeProperty('transition-property');
      }, duration);
    }, 1);
  }
  
  var fadeToggle = (target, duration = 500) => {
    if (window.getComputedStyle(target).display === 'none') {
      return fadeIn(target, duration);
    } else {
      return fadeOut(target, duration);
    }
  }
  
  let slideUp = (target, duration=500) => {
    target.style.transitionProperty = 'height, margin, padding';
    target.style.transitionDuration = duration + 'ms';
    target.style.boxSizing = 'border-box';
    target.style.height = target.offsetHeight + 'px';
    target.offsetHeight;
    target.style.overflow = 'hidden';
    target.style.height = 0;
    target.style.paddingTop = 0;
    target.style.paddingBottom = 0;
    target.style.marginTop = 0;
    target.style.marginBottom = 0;
    window.setTimeout( () => {
      target.style.display = 'none';
      target.style.removeProperty('height');
      target.style.removeProperty('padding-top');
      target.style.removeProperty('padding-bottom');
      target.style.removeProperty('margin-top');
      target.style.removeProperty('margin-bottom');
      target.style.removeProperty('overflow');
      target.style.removeProperty('transition-duration');
      target.style.removeProperty('transition-property');
      //alert("!");
    }, duration);
  }

  let slideDown = (target, duration=500) => {
    target.style.removeProperty('display');
    let display = window.getComputedStyle(target).display;

    if (display === 'none')
      display = 'block';

    target.style.display = display;
    let height = target.offsetHeight;
    target.style.overflow = 'hidden';
    target.style.height = 0;
    target.style.paddingTop = 0;
    target.style.paddingBottom = 0;
    target.style.marginTop = 0;
    target.style.marginBottom = 0;
    target.offsetHeight;
    target.style.boxSizing = 'border-box';
    target.style.transitionProperty = "height, margin, padding";
    target.style.transitionDuration = duration + 'ms';
    target.style.height = height + 'px';
    target.style.removeProperty('padding-top');
    target.style.removeProperty('padding-bottom');
    target.style.removeProperty('margin-top');
    target.style.removeProperty('margin-bottom');
    window.setTimeout( () => {
      target.style.removeProperty('height');
      target.style.removeProperty('overflow');
      target.style.removeProperty('transition-duration');
      target.style.removeProperty('transition-property');
    }, duration);
  }
  var slideToggle = (target, duration = 500) => {
    if (window.getComputedStyle(target).display === 'none') {
      return slideDown(target, duration);
    } else {
      return slideUp(target, duration);
    }
  }