Alerts Only Showing When Message != undefined

The title says it all

by db_dev

HTML

<script src="//code.jquery.com/jquery-3.3.1.slim.min.js"></script>
<link rel="stylesheet" href="//stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css">
<script src="//cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.0/umd/popper.min.js"></script>
<script src="//stackpath.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.5.0/knockout-min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout.mapping/2.4.1/knockout.mapping.js"></script>
<!-- 
  Bootstrap docs: https://getbootstrap.com/docs
-->

<div id="testBox" class="container">
    <div class="row">
        <div class="col">
            <!-- ko if: statusMsg().length > 0 -->
            <div id="statusAlert" class="alert alert-warning alert-dismissible fade" role="alert" data-bind="css: { show: statusMsg().length > 0 }">
                <span data-bind="text:statusMsg"></span>
                <button type="button" class="close" data-dismiss="alert" aria-label="Close" data-bind="click: statusMsgClose">
                    <span aria-hidden="true">&times;</span>
                </button>
            </div>
            <!-- /ko -->
        </div>
    </div>
</div>

CSS

.row {
    background: #f8f9fa;
    margin-top: 20px;
}

.col {
    border: solid 1px #6c757d;
    padding: 10px;
}

JavaScript

var TestVM = function() {
    var self = this;
    /*
    	// When alert.length != 0, add show class to alert
      If not remove show class
      //If user clicks close, remove class
    */
    // Status
    self.statusMsg = ko.observable("");

    self.statusMsgClose = function() {
        self.statusMsg("");
    };
}

vm = new TestVM();
ko.applyBindings(vm, document.getElementById("testBox"));


$("#statusAlert .close").on('click', function() {
    console.log("Closed");
})
vm.statusMsg("Nothing");