Lazy Loading Plotly from CDN does not populate the `window.Plotly` namespace

[jclark86613]

I want to lazy load Plotly from a CDN in my application, when required. When I dynamically create a <script> tag to fetch the CDN at runtime, the window.Ploty namespace is not populated.

1. Is it possible to support this mechanism?
2. Is there something I need to hook into with the initial page load?

Consuming CDN at application root

When I fetch plotly from a CDN via an html <script> tag added to my applications root. My chart render and work as expected. The file is fetched, initialized and the window.Plotly instance exists.

<!-- WORKS -->
 <script type="text/javascript" src="https://cdn.plot.ly/plotly-2.24.3.min.js"></script> 

Consuming CDN with lazy load

However, if I want to lazy load the CDN by creating the <script> tag only when required. When I do this in typescript, the file is successfully fetched, but the window.Plotly namespace never gets populated:

/** DOES NOT WORK */
const init = (): void => {
  const src = 'https://cdn.plot.ly/plotly-2.35.2.min.js';
  const script: HTMLScriptElement = document.createElement('script');
  script.type = 'text/javascript';
  script.src = src;
  script.onerror = (): void => {
    console.error(`Error loading plotly.js library from ${src}`);
  };

  const head: HTMLHeadElement = document.getElementsByTagName('head')[0];
  head.appendChild(script);

  let counter = 200; // equivalent of 10 seconds...
  // Checks if the plotly.js library is loaded by looking for the global Plotly variable.
  const checkLoad = (): void => {
    const plotly = (window as PlotlyWindow).Plotly;
    if (plotly) {
      // ready
      // do something
    } else if (counter > 0) {
      // wait
      counter--;
      setTimeout(checkLoad, 50);
    } else {
      // expire
      throw new Error(`Error loading plotly.js library from ${src}. Timeout.`);
    }
  };
  checkLoad();
};