Bootstrap 4 center navbar brand with collapse

Question

Bootstrap 4 Alpha 6

I cant seem to figure out how to get both the right links and left link to both collapse. Right now only the right hand side link collapses.

<nav id="topNav" class="navbar fixed-top navbar-toggleable-sm navbar-inverse bg-inverse">
<button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target=".navbar-collapse">
    Menu
</button>
<div class="navbar-collapse collapse">
    <ul class="nav navbar-nav">
        <li class="nav-item">
            <a class="nav-link" href="#">Link</a>
        </li>
        <li class="nav-item">
            <a class="nav-link" href="#">Link</a>
        </li>
        <li class="nav-item">
            <a class="nav-link" href="#">Link</a>
        </li>
        <li class="nav-item">
            <a class="nav-link" href="#">Link</a>
        </li>
    </ul>
</div>

<a class="navbar-brand mx-auto" href="#">NavBar</a>

<div class="navbar-collapse collapse">
    <ul class="nav navbar-nav ml-auto">
        <li class="nav-item">
            <a class="nav-link" href="#">About</a>
        </li>
    </ul>
</div>

Answer 1

You should wrap both the menus ul in one navbar-collapse div. Toggle Menu button will only target one collapse div not multiple. As earlier there were two navbar-collapse.

Here is code you should use.

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" integrity="sha384-rwoIResjU2yc3z8GV/NPeZWAv56rSmLldC3R/AZzGRnGxQQKnKkoFVhFQhNUwEyJ" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.1.1.slim.min.js" integrity="sha384-A7FZj7v+d/sdmMqp/nOQwliLvUsJfDHW+k9Omg/a/EheAdgtzNs3hpfag6Ed950n" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>
<nav id="topNav" class="navbar fixed-top navbar-toggleable-sm navbar-inverse bg-inverse">
<button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target=".navbar-collapse">
    Menu
</button>
  <a class="navbar-brand mx-auto" href="#">NavBar</a>

<div class="navbar-collapse collapse">
    <ul class="nav navbar-nav">
        <li class="nav-item">
            <a class="nav-link" href="#">Link</a>
        </li>
        <li class="nav-item">
            <a class="nav-link" href="#">Link</a>
        </li>
        <li class="nav-item">
            <a class="nav-link" href="#">Link</a>
        </li>
        <li class="nav-item">
            <a class="nav-link" href="#">Link</a>
        </li>
    </ul>
  <ul class="nav navbar-nav ml-auto">
        <li class="nav-item">
            <a class="nav-link" href="#">About</a>
        </li>
    </ul>
</div>
</nav>

Answer 2

Currently in alpha 6, the collapse only supports a single target..

Update Bootstrap 4.1

You can absolute position the brand on larger screens, and use a single collapse for the 2 navbars.

@media (min-width: 768px) {
.navbar-brand
    {
        position: absolute;
        left: 50%;
        transform: translateX(-50%);
    }
}

http://www.codeply.com/go/Sh05HDqIh1

Also see:
Center an element in Bootstrap 4 Navbar
How to center nav-items in Bootstrap?