试试这个。 我用href:js添加了so test菜单项，因为这是控制台日志中的代码段位置链接。

菜单打开基于a href链接和当前位置。

编辑:

按照注释中的要求，在所有主菜单类别上添加了点击事件。 如果单击了一个，它将首先隐藏所有子菜单（如果之前显示了任何子菜单，则隐藏），然后只显示单击的子菜单项。

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window.addEventListener("load", function() {
  const page = location.href.split("/").pop();

  console.log(location.href);
  console.log(page);

  [...document.querySelectorAll(".nav_bar > .menu > .item > .sub_menu a")].forEach(link => {
    if (link.href.endsWith(page)) {
      link.setAttribute("style", "background-color: red;");
      link.parentElement.setAttribute("style", "max-height: 10em");
    }
  })
})

const menus = document.querySelectorAll(".nav_bar > .menu > .item ")
for (const menu of menus) {
  menu.addEventListener('click', function(event) {

    [...document.querySelectorAll(".nav_bar > .menu > .item > .sub_menu a")].forEach(link => {
      link.parentElement.setAttribute("style", "max-height: 0em");
    })
    this.getElementsByClassName("sub_menu")[0].setAttribute("style", "max-height: 10em");
  })
}

.nav_bar {
  font-family: sans-serif;
  font-size: 20px;
  width: 250px;
  height: 100vh;
  position: fixed;
  top: 0px;
  left: 0px;
}

.nav_bar .nav_header {
  text-align: center;
  margin: 0;
  padding: 0;
}

.nav_bar .nav_header .nav_logo {
  width: 180px;
}

.nav_bar .menu {
  margin: 20px;
  overflow: hidden;
}

.nav_bar .menu .item {
  display: block;
  margin: 20px;
  position: relative;
}

.nav_bar .menu .item .sub_menu {
  overflow: hidden;
  -webkit-transition: 0.3s;
  transition: 0.3s;
  max-height: 0;
}

.nav_bar .menu .item .sub_menu a::before {
  content: '';
  width: 2px;
  background: #280F98;
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
}

.nav_bar .menu .item .sub_menu a {
  display: block;
  font-size: 14px;
  padding: 10px 5px 10px 10px;
  position: relative;
}

.nav_bar .menu .item:target .sub_menu {
  max-height: 10em;
}

<nav class="nav_bar">
  <div class="menu">
    <div class="item" id="our_work">
      <a href="#our_work" class="button">Our Work</a>
      <div class="sub_menu">
        <a href="js">SO TEST</a>
        <a href="our_work">Our mission</a>
        <a href="our_work#goals">Goals</a>
        <a href="our_work#initiatives">Initiatives</a>

      </div>
    </div>
    <div class="item" id="performances">
      <a href="#performances" class="button">Showcase</a>
      <div class="sub_menu">
        <a href="#">2020</a>
        <a href="#">2019</a>
        <a href="#">2018</a>
        <a href="#">2017</a>

      </div>
    </div>
    <div class="item" id="concerts">
      <a href="#concerts" class="button">Talent</a>
      <div class="sub_menu">
        <a href="#">Concerts 1</a>
        <a href="#">Concerts 2</a>
        <a href="#">Concerts 3</a>

      </div>
    </div>
    <div class="item" id="shop">
      <a href="#shop" class="button">Shop</a>
      <div class="sub_menu">
        <a href="#">Shop 1</a>
        <a href="#">Shop 2</a>
        <a href="#">Shop 3</a>

      </div>
    </div>
  </div>
</nav>