The simple starter plotly.js not rendering a graph--do you see anything that is not as it should be?

Your advice appreciated (tried with the script code where it is & also within the head):

Code did not make it with the post. Trying again:

<script src=""></script>
<div id="tester" style="width:600px;height:250px;"></div>

    TESTER = document.getElementById('tester');
    Plotly.plot(TESTER, [{
    x: [1, 2, 3, 4, 5],
    y: [1, 2, 4, 8, 16] }], {
    margin: { t: 0 } } );

Everything looks fine to me.

Can you try opening the browser console and see if there are any errors being logged?