Make importing fail if URL has changed (for SPA, PJAX, and History API)

[falsandtru]

After url and dom are changed by SPA or PJAX, requested scripts must NOT be evaluated. So importing must have failed if url has changed.

If it is not a module script, we can cancel the evaluation of that. But if it is a module script, we cannot cancel the evaluation of that.

Here is my code having this problem.

  const url = new URL(standardizeUrl(location.href));
  if (script.type.toLowerCase() === 'module') {
    return wait.then(() => import(script.src))
      .then(
        () => (
          void script.dispatchEvent(new Event('load')),
          Right(script)),
        reason => (
          void script.dispatchEvent(new Event('error')),
          Left(new FatalError(reason instanceof Error ? reason.message : reason + ''))));
  }
  else {
    return script.hasAttribute('defer')
      ? wait.then(evaluate)
      : evaluate();
  }

  function evaluate() {
    try {
      if (new URL(standardizeUrl(location.href)).path !== url.path) throw new FatalError('Expired.');
      if (skip.has(standardizeUrl(location.href))) throw new FatalError('Expired.');
      void (0, eval)(code);
      script.hasAttribute('src') && void script.dispatchEvent(new Event('load'));
      return Right(script);
    }
    catch (reason) {
      script.hasAttribute('src') && void script.dispatchEvent(new Event('error'));
      return Left(new FatalError(reason instanceof Error ? reason.message : reason + ''));
    }
  }

https://github.com/falsandtru/pjax-api/blob/ae05475a829974d634b46ac346939a599c90545b/src/layer/domain/router/module/update/script.ts#L123-L152

[falsandtru]

Moved to https://github.com/whatwg/loader/issues/158

[falsandtru]

Since https://github.com/whatwg/loader/issues/158

[domenic]

This seems like a question for StackOverflow, not the spec. It's a lot of code that I don't have the bandwidth to debug for you, but hopefully volunteers there can help.

[matthewp]

I believe this is a feature request, aborting an import.

[matthewp]

If I'm correct in that interpretation you might be interested in https://github.com/tc39/proposal-dynamic-import/issues/42 @falsandtru

[falsandtru]

I believe this is a feature request, aborting an import.

I think so, but @caridy redirected to here. This issue demonstrate a need of cancelable dynamic import. This issue must be resolved by design of es or whatwg. It is impossible to resolve this case at downstream.