failed-to-load

Find script tags that have failed to load when document's readyState is complete.

Add this attribute "onload" with "this.loaded=1" in its value (onload="this.loaded=1")

<script src="my-script-922a511f02d148e4c9390526d85ca519.js" onload="this.loaded=1"></script>
<script src="other-script-693e810ff27604e6da274da4c77e136c.js" onload="this.loaded=1"></script>

Register check for window load

import { register } from 'failed-to-load';
register();

This will throw an ayncronous error to be caught by your global onerror callback.

Error{
  message: `Failed to load necessary script tags upon window load
my-script-922a511f02d148e4c9390526d85ca519.js
other-script-693e810ff27604e6da274da4c77e136c.js`,
  code: 'ERROR_NECESSARY_SCRIPT_NOT_LOADED',
  files: [
    [object HTMLScriptElement],
    [object HTMLScriptElement]
  ]
}

Alternatively, you can register a callback to catch the error (then it will not be thrown)

register(
  error => logger.warn(error)
);

Check and report manually:

import { check } from 'failed-to-load';

window.addEventListener('load', () => {
  const missing = check();
  if (missing.length) {
    logger.warn({
      message: 'script files not loaded on page load',
      files: missing.map(({ src }) => src)
    })
  }
});