如何使用自定义选择下拉列表筛选项目?

//dropdown
for (const dropdown of document.querySelectorAll(".custom__select-wrapper")) {
  dropdown.addEventListener("click", function () {
    this.querySelector(".custom__select").classList.toggle("open");
  });
}

for (const option of document.querySelectorAll(".custom__option")) {
  option.addEventListener("click", function () {
    if (!this.classList.contains("selected")) {
      this.parentNode
        .querySelector(".custom__option.selected")
        .classList.remove("selected");
      this.classList.add("selected");
      this.closest(".custom__select").querySelector(
        ".custom__select-trigger span"
      ).textContent = this.textContent;
    }
  });
}

window.addEventListener("click", function (e) {
  for (const select of document.querySelectorAll(".custom__select")) {
    if (!select.contains(e.target)) {
      select.classList.remove("open");
    }
  }
});

//filter
document.addEventListener("DOMContentLoaded", function (event) {
  const filter = document.querySelector("#filter");
  const articles = document.querySelectorAll(".article");

  filter.addEventListener("change", (event) => {
    if (event.target.value != "") {
      for (let i = 0; i < articles.length; i++) {
        if (articles[i].dataset.itemName == event.target.value) {
          articles[i].classList.remove("hidden-item");
        } else {
          articles[i].classList.add("hidden-item");
        }
      }
    } else {
      for (let i = 0; i < articles.length; i++) {
        articles[i].classList.remove("hidden-item");
      }
    }
  });
});

.hidden-item {
  display: none;
}

.custom__select {
  position: relative;
  display: flex;
  flex-direction: column;
}
.custom__select-wrapper {
  position: relative;
  user-select: none;
  width: 100%;
}
.custom__select-trigger {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 22px;
  font-size: 20px;
  font-weight: 300;
  color: #3b3b3b;
  height: 60px;
  line-height: 60px;
  background: #ffffff;
  cursor: pointer;
}
.custom__options {
  position: absolute;
  display: block;
  background-color: #005fec;
  top: 100%;
  left: 0;
  right: 0;
  border-top: 0;
  transition: all 0.5s;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  z-index: 2;
}
.custom__select.open .custom__options {
  opacity: 1;
  visibility: visible;
  pointer-events: all;
  color: #fff;
}
.custom__option {
  position: relative;
  display: block;
  padding: 0 22px 0 28px;
  font-size: 22px;
  font-weight: 300;
  color: #fff;
  line-height: 60px;
  cursor: pointer;
  transition: all 0.5s;
}
.custom__option:hover {
  cursor: pointer;
  background-color: #b2b2b2;
}
.custom__option.selected {
  color: #ffffff;
}
.custom__option.selected::before {
  content: "•";
  margin-left: -12px;
  padding-right: 8px;
}

/* arrow */
.arrow {
  position: relative;
  height: 15px;
  width: 15px;
}
.arrow::before, .arrow::after {
  content: "";
  position: absolute;
  bottom: 0px;
  width: 0.15rem;
  height: 100%;
  transition: all 0.5s;
}
.arrow::before {
  left: -5px;
  transform: rotate(45deg);
  background-color: #394a6d;
}
.arrow::after {
  left: 5px;
  transform: rotate(-45deg);
  background-color: #394a6d;
}
.open .arrow::before {
  left: -5px;
  transform: rotate(-45deg);
}
.open .arrow::after {
  left: 5px;
  transform: rotate(45deg);
}
.arrow::after {
  left: 5px;
  transform: rotate(-45deg);
  background-color: #394a6d;
}
.open .arrow::before {
  left: -5px;
  transform: rotate(-45deg);
}
.open .arrow::after {
  left: 5px;
  transform: rotate(45deg);
}

<div class="wrapper">
  <div class="custom__select-wrapper">
    <div class="custom__select">
      <div class="custom__select-trigger"><span>Story Type</span>
        <div class="arrow"></div>
      </div>
      <div class="custom__options" id="filter">
        <span class="custom__option selected" selected="">All</span>
        <span class="custom__option" value="news">News and Media</span>
        <span class="custom__option" value="analysis">Analysis</span>
        <span class="custom__option" value="press">Press Releases</span>
      </div>
    </div>
  </div>
</div>

    <div class="list article news 2020" data-item-name="news">
      <ul>
        <li><strong>Company:</strong> Company 1</li>
        <li><strong>Start Date:</strong> March 26, 2020</li>
        <li><strong>Title:</strong> <a href="#" target="_blank">Article Title</a></li>
        <li><strong>Type:</strong> news</li>
      </ul>
    </div>
   
    <div class="list article news 2019" data-item-name="news">
      <ul>
        <li><strong>Company:</strong> Company 2</li>
        <li><strong>Start Date:</strong> November 17, 2019</li>
        <li><strong>Title:</strong> <a href="#" target="_blank">Article Title</a></li>
        <li><strong>Type:</strong> news</li>
      </ul>
    </div>
   
    <div class="list article analysis 2017" data-item-name="analysis">
      <ul>
        <li><strong>Company:</strong> Company 3</li>
        <li><strong>Start Date:</strong> March 15, 2017</li>
        <li><strong>Title:</strong> <a href="#" target="_blank">Article Title</a></li>
        <li><strong>Type:</strong> analysis</li>
      </ul>
    </div>
   
    <div class="list article analysis 2016" data-item-name="analysis">
      <ul>
        <li><strong>Company:</strong> Company 4</li>
        <li><strong>Start Date:</strong> January 3, 2016</li>
        <li><strong>Title:</strong> <a href="#" target="_blank">Article Title</a></li>
        <li><strong>Type:</strong> analysis</li>
      </ul>
    </div>
   
    <div class="list article press 2014" data-item-name="press">
      <ul>
        <li><strong>Company:</strong> Company 5</li>
        <li><strong>Start Date:</strong> March 13, 2014</li>
        <li><strong>Title:</strong> <a href="#" target="_blank">Aritcle Title</a></li>
        <li><strong>Type:</strong> press</li>
      </ul>
    </div>
   
    <div class="list article press 2013" data-item-name="press">
      <ul>
        <li><strong>Company:</strong> Company 6</li>
        <li><strong>Start Date:</strong> March 6, 2013</li>
        <li><strong>Title:</strong> <a href="#" target="_blank">Article Title</a></li>
        <li><strong>Type:</strong> press</li>
      </ul>
    </div>