$(...).selectpicker is not a function

If you have another jquery.js reference that is loading after bootstrap-select.min.js it will wipe out $(...).selectpicker function and other functions. Make sure that bootstrap-select.min.js is loaded last.

For whatever reason this needs to be called through jquery

$("#MyDropDown").selectpicker('render');

This (non jquery) generates the error:

mdd = document.getElementById("MyDropDown");
mdd.selectpicker('render');

I'm interested to know why.

Try to load bootstrap before bootstrap-select ;-)

<link rel="stylesheet" type="text/css" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.12.2/css/bootstrap-select.min.css">

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.12.2/js/bootstrap-select.min.js"></script>