sub menu in dropodown menu in bootstrap menu 4 code example

Example 1: bootstrap 4 dropdown

<div class="dropdown">
  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Dropdown button
  </button>
  <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
    <a class="dropdown-item" href="#">Action</a>
    <a class="dropdown-item" href="#">Another action</a>
    <a class="dropdown-item" href="#">Something else here</a>
  </div>
</div>

Example 2: dropdown bootstrap

Bootstrap Dropdown menu with seach button<div class="collapse navbar-collapse justify-content-between" id="navbarCollapse">
            <div class="navbar-nav">
                <div class="nav-item dropdown">
                    <a href="#" class="nav-link dropdown-toggle" data-toggle="dropdown">MANAGEMENT</a>
                    <div class="dropdown-menu">
                        <a href="#" class="dropdown-item">Man</a>
                        <a href="#" class="dropdown-item">Man</a>
                        <a href="#" class="dropdown-item">Man</a>
                    </div>
                </div>
            </div>
            
            <div class="collapse navbar-collapse justify-content-between" id="navbarCollapse">
            <div class="navbar-nav">
                <div class="nav-item dropdown">
                    <a href="#" class="nav-link dropdown-toggle" data-toggle="dropdown">PROJECT</a>
                    <div class="dropdown-menu">
                        <a href="#" class="dropdown-item">Pro</a>
                        <a href="#" class="dropdown-item">Pro</a>
                        <a href="#" class="dropdown-item">Pro</a>
                    </div>
                </div>
            </div>

            <div class="navbar-nav">
                <a href="#" class="nav-item nav-link">LOGIN/REGISTER</a>
            </div>
        </div>
    </nav>
</div>