Uncaught ReferenceError: BVSelect is not defined

[TestO2015]

I have loaded the BVSelect JS and CSS files into my Javascript ES6 file and created a #selectbox element.

When I try to use new BVSelect() it fails with:

Uncaught ReferenceError: BVSelect is not defined

The browser shows that the .js and .css files are loaded succesfully and my code intellisense does pick up the BVSelect class.

Here's my javascript:

    $(`
    <select id="selectbox">
      <option data-separator="true"> Select Option </option>
      <option value="1"> Option 1 </option>
      <option value="2"> Option 2 </option>
      <option value="3" disabled> Option 3 </option>
      <option value="4"> Option 4 </option>
    </select>`).appendTo(this.$contentDiv);

    var demo = new BVSelect('#selectbox');