<fieldset class="formSlider">
        <legend class="applicationForm__text">Выберите количество серебра (млн)</legend>
        <input
          class="formSlider__range"
          type="range"
          min="1"
          max="50"
          step="1"
          
          id="sliderRange"
          list="ticks"
        />
<!-- for ticks in range input -->
        <datalist id="ticks" class="formSlider__tickList"></datalist>

        <input class="formSlider__input" type="number" id="totalQuantity" />
      </fieldset>

$runnableTrack: 8px;

.formSlider {
  display: flex;
  flex-direction: column;
  margin: 0 0 25px 0;

  &__tickList {
    position: relative;
    display: flex;
    justify-content: space-between;
    height: auto;
    bottom: 15px;
    height: 20px;
    overflow: hidden;
    /* disable text selection */
    -webkit-user-select: none; /* Safari */
    -moz-user-select: none; /* Firefox */
    -ms-user-select: none; /* IE10+/Edge */
    user-select: none; /* Standard */
    /* disable click events */
    pointer-events: none;

    option {
      width: 3px;

      background-color: #25beb3;
      background-color: black;
      &:first-of-type,
      &:last-of-type {
        opacity: 0;
        visibility: hidden;
      }
    }
  }

  legend {
    padding: 0 0 45px 0;
  }
  &__range {
    width: 100%;
    -webkit-appearance: none;
    background: transparent;
    cursor: pointer;
    &:focus {
      outline: none;
    }
    &::-ms-track {
      background: transparent;
      border-color: transparent;
      color: transparent;
    }

    ::-ms-ticks-before {
      display: block;
      color: black;
    }
    // /* circle */
    &::-webkit-slider-thumb {
      -webkit-appearance: none;
      height: 20px;
      width: 20px;
      border-radius: 100%;
      background-color: #25beb3;
      cursor: pointer;
      margin: -5px;
    }
    // /* circle firefox */
    &::-moz-range-thumb {
      -webkit-appearance: none;
      height: 20px;
      width: 20px;
      border-radius: 100%;
      background-color: #25beb3;
      cursor: pointer;
    }

    /* runnable track */
    &::-webkit-slider-runnable-track {
      width: 100%;
      height: $runnableTrack;
      cursor: pointer;
      background: #207d7e;
      border-radius: 4px;
    }

    /* runnable track firefox*/
    &::-moz-range-track {
      width: 100%;
      height: $runnableTrack;
      cursor: pointer;
      background: #207d7e;
      border-radius: 4px;
    }
  }

  &__input {
    border: 2px solid #25beb3;
    background: transparent;
    height: 56px;
    max-width: 235px;
    width: 100%;
    padding: 0 25px;
    color: #ffffff;
    font-family: "Gotham Pro";
    font-size: 20px;
    font-weight: 700;
    margin: 25px 0 0 auto;
    &::-webkit-outer-spin-button,
    &::-webkit-inner-spin-button {
      -webkit-appearance: none;
    }
  }
}

const totalInput = document.getElementById("totalQuantity");
const rangeTickList = document.getElementById("ticks");
const rangeSlider = document.getElementById("sliderRange");

window.addEventListener("DOMContentLoaded", function () {
  const maxTicks = rangeSlider.getAttribute("max");

  for (let i = 0; i < maxTicks; i++) {
    const option = document.createElement("option");
    rangeTickList.appendChild(option);
  }
  console.log(rangeTickList.children.length);

});