Use Promise.allSettled instead of Promise.all for partial failure handling

[umairkarel]

Promise.allSettled should be used

facebook-tag/template.js

Line 162 in 24c5fdc

Promise.all(requests)

Description

The current implementation uses Promise.all(requests) but later assumes that all request results will always be available, even if some requests fail.

However, Promise.all() rejects immediately when any promise rejects, which means:

• The .then(results => { ... }) block will not execute if any request fails or times out
• Per-request logging inside results.forEach(...) will be skipped
• Failures are handled only by .catch(), losing visibility into successful responses

This behavior limits executing, evaluating and logging each individual requests and responses.

Solution

Replace Promise.all() with Promise.allSettled() so that all requests are awaited, regardless of individual failures.

This allows:

• Logging of both successful and failed requests
• Accurate detection of partial failures
• Allows all requests to be executed even if one or more requests fail in between.

Proposed Implementation

Promise.allSettled(requests)
  .then((results) => {
    let someRequestFailed = false;

    results.forEach((result) => {
      if (result.status === 'fulfilled') {
        const res = result.value;

        log({
          Name: 'Facebook',
          Type: 'Response',
          TraceId: traceId,
          EventName: mappedEventData.event_name,
          ResponseStatusCode: res.statusCode,
          ResponseHeaders: res.headers,
          ResponseBody: res.body
        });

        if (res.statusCode < 200 || res.statusCode >= 300) {
          someRequestFailed = true;
        }
      } else {
        someRequestFailed = true;

        log({
          Name: 'Facebook',
          Type: 'Response',
          TraceId: traceId,
          EventName: mappedEventData.event_name,
          Message: 'Request failed or timed out.',
          Reason: JSON.stringify(result.reason)
        });
      }
    });

    if (!data.useOptimisticScenario) {
      if (someRequestFailed) data.gtmOnFailure();
      else data.gtmOnSuccess();
    }
  });

[giovaniortolani]

Hi @umairkarel, Promise.allSettled doesn't exist in the GTM Sandboxed API (ref).

However, your suggestion is good, and we'll consider a way to implement it.

[umairkarel]

Hi @giovaniortolani, I checked and it doesn't provide directly.

You could probably use polyfill for allSettled

Promise.allSettled = Promise.allSettled || ((promises) => Promise.all(
    promises.map(p => p
        .then(result => ({
            status: "fulfilled",
            value: result
        }))
        .catch(error => ({
            status: "rejected",
            reason: error
        }))
    )
));