Multi-Level NavBar in Angular 6 Bootstrap 4 - css

Question

(UPDATE: Resolved - i had to add the javascript in $(document).ready(function(), which i was missing. The below eg worked perfect for me.)
I am trying to make a Multi-Level Navbar work with Angular 6 & Bootstrap 4.
How do i expand and colapse sub-menu's on click or hover? I want the menu to expand to the right...
Eg: I found a solution on this link - but i am not sure how to inject Javascript in a Angular component.
https://codepen.io/surjithctly/pen/PJqKzQ
Here are my version details
+-- bootstrap#4.1.3
+-- jquery#3.3.1
+-- popper.js#1.14.4
Below is my Navbar Code
<nav class="navbar navbar-expand-lg navbar-dark">
<a class="navbar-brand" href="#" style="color: red;">
My NAVBAR
</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav mr-auto">
<li class="nav-item">
<a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdownHI" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Menu
</a>
<ul class="dropdown-menu" aria-labelledby="navbarDropdownHI">
<li><a class="dropdown-item" href="#">Action</a></li>
<li class="nav-item dropdown"><a class="dropdown-item dropdown-toggle" href="#">Submenu</a>
<ul class="dropdown-menu">
<li><a class="dropdown-item" href="#">Submenu action</a></li>
<li><a class="dropdown-item" href="#">Another submenu action</a></li>
</ul>
</li>
<li class="dropdown-divider"></li>
<li><a class="dropdown-item" href="#">View All</a></li>
</ul>
</li>
<li class="nav-item">
<a class="nav-link disabled" href="#">Disabled</a>
</li>
</ul>
</div>
</nav>

Answer 1

You need to add custom styles along with the following html
.dropdown-submenu {
position: relative;
}
.dropdown-submenu>.dropdown-menu {
top: 0;
left: 100%;
margin-top: -6px;
margin-left: -1px;
-webkit-border-radius: 0 6px 6px 6px;
-moz-border-radius: 0 6px 6px;
border-radius: 0 6px 6px 6px;
}
.dropdown-submenu:hover>.dropdown-menu {
display: block;
}
.dropdown-submenu>a:after {
display: block;
content: " ";
float: right;
width: 0;
height: 0;
border-color: transparent;
border-style: solid;
border-width: 5px 0 5px 5px;
border-left-color: #ccc;
margin-top: 5px;
margin-right: -10px;
}
.dropdown-submenu:hover>a:after {
border-left-color: #fff;
}
.dropdown-submenu.pull-left {
float: none;
}
.dropdown-submenu.pull-left>.dropdown-menu {
left: -100%;
margin-left: 10px;
-webkit-border-radius: 6px 0 6px 6px;
-moz-border-radius: 6px 0 6px 6px;
border-radius: 6px 0 6px 6px;
}
<div class="container">
<div class="row">
<div class="dropdown">
<button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Dropdown
</button>
<ul class="dropdown-menu multi-level" role="menu" aria-labelledby="dropdownMenu">
<li class="dropdown-item">Some action</li>
<li class="dropdown-item">Some other action</li>
<li class="dropdown-divider"></li>
<li class="dropdown-submenu">
<a class="dropdown-item" tabindex="-1" href="#">Hover me for more options</a>
<ul class="dropdown-menu">
<li class="dropdown-item"><a tabindex="-1" href="#">Second level</a></li>
<li class="dropdown-submenu">
<a class="dropdown-item" href="#">Even More..</a>
<ul class="dropdown-menu">
<li class="dropdown-item">3rd level</li>
<li class="dropdown-submenu"><a class="dropdown-item" href="#">another level</a>
<ul class="dropdown-menu">
<li class="dropdown-item">4th level</li>
<li class="dropdown-item">4th level</li>
<li class="dropdown-item">4th level</li>
</ul>
</li>
<li class="dropdown-item">3rd level</li>
</ul>
</li>
<li class="dropdown-item">Second level</li>
<li class="dropdown-item">Second level</li>
</ul>
</li>
</ul>
</div>
</div>
</div>