кастомный скролл для ie 11

class ScrollBar {
  actor = null;
  spy = null;
  jack = null;
  lastPos = -1;
  scrollTimeout = null;
  scrollInterval=null;
  scrollDirection = 0;
  jackHolding = false;
  active = false;
  activeTimeout = null;
  constructor(props) {
    Object.assign(this, props);
    if (!this.actor instanceof Element) {
      throw new Error("ScrollBar#actor");
    }
    if (!this.spy instanceof Element) {
      throw new Error("ScrollBar#actor");
    }
    this.jack = document.createElement('div');
    this.jack.classList.add('jack');
    this.actor.appendChild(this.jack);
  }
  enable() {
    this.updateSize();
    this.spy.addEventListener("scroll", (e) => this.onSpyScroll(e));
    this.actor.addEventListener("mousedown", (e) => this.onActorMouseDown(e));
    this.actor.addEventListener("mouseup", (e) => this.onActorMouseUp(e));
    this.actor.addEventListener("mouseout", (e) => this.onActorMouseOut(e));
    this.actor.addEventListener("mouseenter", (e) => this.onActorMouseEnter(e));
    this.actor.addEventListener("mouseleave", (e) => this.onActorMouseLeave(e));
    this.jack.addEventListener("mousedown", (e) => this.onJackMouseDown(e));
    window.addEventListener("resize", (e) => this.onWindowResize(e));
    window.addEventListener("mouseup", (e) => this.onWindowMouseUp(e));
    window.addEventListener("mousemove", (e) => this.onWindowMouseMove(e));
    window.addEventListener("blur", (e) => this.onWindowBlur(e));
  }
  disable() {
    this.spy.removeEventListener("scroll", (e) => this.onSpyScroll(e));
    this.actor.removeEventListener("mousedown", (e) => this.onActorMouseDown(e));
    this.actor.removeEventListener("mouseup", (e) => this.onActorMouseUp(e));
    this.actor.removeEventListener("mouseout", (e) => this.onActorMouseOut(e));
    this.actor.removeEventListener("mouseenter", (e) => this.onActorMouseEnter(e));
    this.actor.removeEventListener("mouseleave", (e) => this.onActorMouseLeave(e));
    this.jack.removeEventListener("mousedown", (e) => this.onJackMouseDown(e));
    window.removeEventListener("resize", (e) => this.onWindowResize(e));
    window.removeEventListener("mouseup", (e) => this.onWindowMouseUp(e));
    window.removeEventListener("mousemove", (e) => this.onWindowMouseMove(e));
    window.removeEventListener("blur", (e) => this.onWindowBlur(e));
  }
  onSpyScroll() {
    if(!this.active){
      this.onStartScroll();
    } else {
      clearTimeout(this.activeTimeout);
    }
    this.activeTimeout = setTimeout(()=>this.onEndScroll(),50);
    this.updatePos();
  }
  onActorMouseDown(e) {
    this.scrollDirection = e.clientX < this.jack.offsetLeft ? -1 : e.clientX > this.jack.offsetLeft + this.jack.clientWidth ? 1 : 0;
    this.startScroll();
  }
  onActorMouseUp(e) {
    this.stopScroll();
  }
  onActorMouseOut(e) {
    this.stopScroll();
  }
  onActorMouseEnter(e) {
    this.actor.classList.add('hover');
  }
  onActorMouseLeave(e) {
    this.actor.classList.remove('hover');
  }
  onJackMouseDown(e) {
    e.stopPropagation();
    this.spy.classList.add('disable-smooth');
    this.jackHolding = true;
  }
  onWindowResize() {
    this.updateSize();
  }
  onWindowMouseUp(e) {
    this.stopScroll();
  }
  onWindowMouseMove(e){
    if(this.jackHolding){
      const [or] = this.update();
      this.spy.scrollLeft += ~~( e.movementX * or );
    }
  }
  onWindowBlur(e) {
    this.stopScroll();
  }
  onStartScroll(){
    this.actor.classList.add('active');
    this.active = true;
  }
  onEndScroll(){
    this.actor.classList.remove('active');
    this.active = false;
  }
  startScroll(){
    this.spy.scrollLeft += this.spy.clientWidth * this.scrollDirection;
    // this.actor.classList.add('scrolling');
    this.scrollTimeout= setTimeout(()=>{
      this.scrollTimeout = null;
      this.spy.classList.add('disable-smooth');
      this.spy.scrollLeft += ~~(this.spy.clientWidth * this.scrollDirection / 4);
      this.scrollInterval = setInterval(()=>{
        this.spy.scrollLeft += ~~(this.spy.clientWidth * this.scrollDirection / 4);
      },20);
    },750);
  }
  stopScroll(){
    this.jackHolding = false;
    if(this.scrollTimeout) clearTimeout(this.scrollTimeout);
    if(this.scrollInterval) clearInterval(this.scrollInterval);
    // this.actor.classList.remove('scrolling');
    this.spy.classList.remove('disable-smooth');
    this.scrollTimeout = null;
    this.scrollInterval = null;
  }
  updateSize() {
    const [,jw,jl] = this.update();
    requestAnimationFrame(() => {
      this.jack.style.width = jw + "px";
      this.jack.style.left = jl + "px";
    });
  }
  updatePos() {
    const [,,jl] = this.update();
    if (this.lastPos != jl) {
      this.lastPos = jl;
      requestAnimationFrame(() => {
        this.jack.style.left = jl + "px";
      });
    }
  }
  update(){
    const stw = this.spy.scrollWidth,
      svw = this.spy.clientWidth,
      ssl = this.spy.scrollLeft,
      ssmx = stw - svw,
      aw = this.actor.clientWidth,
      jw = ~~(svw ** 2 / stw),
      jmx = aw - jw,
      or = ssmx / jmx,
      jl = ~~(ssl / or);
    return [or,jw,jl]
  }
}
const scrollBar = new ScrollBar({
  spy: document.querySelector(".spy"),
  actor: document.querySelector(".actor"),
});
scrollBar.enable();

html,
body {
  margin: 0;
  padding: 0;
}
.spy {
  height: calc(100vh - 11px);
  width: 100vw;
  background: #ffffff;
  overflow-x: scroll;
  overflow-y: hidden;
  scroll-behavior: smooth;
}
.spy.disable-smooth {
  scroll-behavior: initial;
}
.content {
  display: inline-block;
  height: calc(100vh - 11px);
  width: calc(100vw * 15);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 304 304' width='304' height='304'%3E%3Cpath fill='%239C92AC' fill-opacity='0.4' d='M44.1 224a5 5 0 1 1 0 2H0v-2h44.1zm160 48a5 5 0 1 1 0 2H82v-2h122.1zm57.8-46a5 5 0 1 1 0-2H304v2h-42.1zm0 16a5 5 0 1 1 0-2H304v2h-42.1zm6.2-114a5 5 0 1 1 0 2h-86.2a5 5 0 1 1 0-2h86.2zm-256-48a5 5 0 1 1 0 2H0v-2h12.1zm185.8 34a5 5 0 1 1 0-2h86.2a5 5 0 1 1 0 2h-86.2zM258 12.1a5 5 0 1 1-2 0V0h2v12.1zm-64 208a5 5 0 1 1-2 0v-54.2a5 5 0 1 1 2 0v54.2zm48-198.2V80h62v2h-64V21.9a5 5 0 1 1 2 0zm16 16V64h46v2h-48V37.9a5 5 0 1 1 2 0zm-128 96V208h16v12.1a5 5 0 1 1-2 0V210h-16v-76.1a5 5 0 1 1 2 0zm-5.9-21.9a5 5 0 1 1 0 2H114v48H85.9a5 5 0 1 1 0-2H112v-48h12.1zm-6.2 130a5 5 0 1 1 0-2H176v-74.1a5 5 0 1 1 2 0V242h-60.1zm-16-64a5 5 0 1 1 0-2H114v48h10.1a5 5 0 1 1 0 2H112v-48h-10.1zM66 284.1a5 5 0 1 1-2 0V274H50v30h-2v-32h18v12.1zM236.1 176a5 5 0 1 1 0 2H226v94h48v32h-2v-30h-48v-98h12.1zm25.8-30a5 5 0 1 1 0-2H274v44.1a5 5 0 1 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0 0 0 6zm-96 0a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm0 16a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm16-32a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm96 0a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm-16-64a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm16-16a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm-32 0a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm0-16a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm-16 0a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm-16 0a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm-16 0a3 3 0 1 0 0-6 3 3 0 0 0 0 6zM49 36a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm-32 0a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm32 16a3 3 0 1 0 0-6 3 3 0 0 0 0 6zM33 68a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm16-48a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm0 240a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm16 32a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm-16-64a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm0 16a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm-16-32a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm80-176a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm16 0a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm-16-16a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm32 48a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm16-16a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm0-32a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm112 176a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm-16 16a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm0 16a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm0 16a3 3 0 1 0 0-6 3 3 0 0 0 0 6zM17 180a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm0 16a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm0-32a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm16 0a3 3 0 1 0 0-6 3 3 0 0 0 0 6zM17 84a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm32 64a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm16-16a3 3 0 1 0 0-6 3 3 0 0 0 0 6z'%3E%3C/path%3E%3C/svg%3E");
}
.actor {
  position: fixed;
  height: 11px;
  width: 100vw;
  right: 0;
  bottom: 0;
  background: #eee;
  transition-property: background-color;
  transition-duration: .2s;
  -webkit-user-drag: none;
  user-select: none;
}
.actor.hover {
  background: #ccc;
  transition-duration: .5s;
}
.jack {
  height: 10px;
  background: #218;
  position: absolute;
  transition-property: background-color, transform;
  transition-duration: .5s;
  transition-timing-function: ease-in-out;
  border-radius: 4px;
  -webkit-user-drag: none;
  user-select: none;
  transform: scaleY(.6);
  /* margin-left: -1px; */
}
.actor.hover .jack {
  background: #31f;
  transform: scaleY(1);
  border-radius: 7px;
  transition-duration: .5s;
  /* margin-left: 0; */
}
.actor.active .jack {
  background: #471696;
  transition-duration: .1s;
}

/* Раскомментируйте эти строчки для того чтобы скрыть оригинальный скрол */
/* 
.spy{
  overflow-y: auto;
  cursor: pointer;
  -ms-overflow-style: none;
  scrollbar-width: none; 
}
.spy::-webkit-scrollbar { 
    display: none; 
} 
*/

    <div class="spy">
      <div class="content" style="font-size: 30pt">
        <div style="width:400px; float: right">
          ◀◀◀◀◀ конец
        </div>
        Скролл вправо ▶▶▶▶▶
      </div>
    </div>
    <div class="actor"></div>