Remove `js-logger` dependency by simolus3 · Pull Request #966 · powersync-ja/powersync-js

simolus3 · 2026-05-15T15:42:02Z

As proposed in #948, this removes the js-logger dependency in favor of a custom logging interface. The idea is that:

The interface should be as simple as possible, and be easy to implement for users with custom logging needs.
This is only used for logs from the SDK, not a general-purpose logging library. We can afford making logging inside the SDK a bit less ergonomic (passing level as a named parameter instead of one method per level) to keep the interface smaller.
Outside of the message, which is always a string, we have additional fields which are well-typed and named (credits to Luc for the idea).
There is no global hierarchy of loggers, and no global createBaseLogger. If you want a PowerSync database to log, you pass a logger in. By default, we use an implementation forwarding logs to console.log.

For the most part, users can keep using the default option and continue to get a default out-of-the-box experience where messages with level info and higher are logged to the console with a [PowerSync] prefix. To customize this:

Implement the PowerSyncLogger interface, and pass an instance of that to PowerSyncDatabase. Or, if you want the default logger but with another minimum severity, use createPowerSyncLogger.
When instantiating a WASQLiteOpenFactory directly, one also needs to pass a logger. The web SDK would forward the one from the database by default.
For log messages forwarded from workers, the way to configure the minimum severity has changed. Before, we'd use the log level of the database logger. Because the logger interface is essentially a sink now and doesn't expose that, we can't do that anymore. Instead,
- For database workers, a logLevel can be passed to WASQLiteOpenFactory, and messages with that level or higher are forwarded to the main tab.
- For sync workers, the minimum log level can be configured as an option when constructing the database.

This is a breaking change, which is why this PR has the v2 branch as a target. The idea is to bundle up changes which we can then release at once.

changeset-bot · 2026-05-15T15:42:08Z

🦋 Changeset detected

Latest commit: e733396

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 16 packages

Name	Type
@powersync/common	Major
@powersync/adapter-sql-js	Patch
@powersync/attachments-storage-react-native	Major
@powersync/attachments	Major
@powersync/drizzle-driver	Major
@powersync/kysely-driver	Major
@powersync/node	Major
@powersync/nuxt	Major
@powersync/op-sqlite	Major
@powersync/react-native	Major
@powersync/react	Major
@powersync/tanstack-react-query	Major
@powersync/vue	Major
@powersync/web	Major
@powersync/diagnostics-app	Patch
@powersync/capacitor	Major

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LucDeCaf

I like the changes outlined here. There's just a few places which seem to be leftovers from an earlier draft, or which didn't get translated as cleanly.

LucDeCaf · 2026-05-29T13:40:49Z

-      this.logger.error(`UploadAttachment error for record ${JSON.stringify(record, null, 2)}`);
+      this.logger.log({
+        level: LogLevels.error,
+        message: `UploadAttachment error for record ${JSON.stringify(record, null, 2)}`


We can probably assign the log's error field to the caught error object.

LucDeCaf · 2026-05-29T13:41:54Z

-      this.logger.error('Downloads failed:', e);
+      this.logger.log({ level: LogLevels.debug, message: 'Finished downloading attachments' });
+    } catch (error) {
+      this.logger.log({ level: LogLevels.error, message: 'Downloads failed:', error });


Nit: ":" after "Downloads failed" doesn't really make sense anymore :)

LucDeCaf · 2026-05-29T13:44:53Z

          // Device came online, process attachments immediately
          this.syncStorage().catch((error) => {
-            this.logger.error('Error syncing storage on connection:', error);
+            this.logger.log({ level: LogLevels.error, message: 'Error syncing storage on connection:', error });


Nit: same as above

LucDeCaf · 2026-05-29T13:46:46Z

+        this.logger.log({
+          level: LogLevels.error,
+          message: `Could not POST streaming to ${path} - ${res.status} - ${res.statusText}: ${text}`
+        });


I think we can assign the log's error to the error created below it before throwing.

LucDeCaf · 2026-05-29T13:48:15Z

-            );
+            this.logger.log({
+              level: LogLevels.debug,
+              message: `Caught exception when uploading. Upload will retry after a delay. Exception: ${(ex as Error).message}`


This is debatable because it's a debug log, but we might want to pass in the error anyways. No strong opinion.

LucDeCaf · 2026-05-29T13:54:18Z

-      console.log(...args);
-      logMessages.push(util.format(...args));
+    const logger: PowerSyncLogger = {
+      log(_level, ...message) {


This looks like it's still using the initial PowerSyncLogger.log(level: number, ...message: any[]) syntax.

LucDeCaf · 2026-05-29T14:02:18Z

-      logger.error('Failed to parse query:', e);
-      handleError(e);
+    } catch (error) {
+      logger?.log({ level: LogLevels.error, message: 'Failed to parse query:', error });


Nit: Same as prior

LucDeCaf · 2026-05-29T14:02:35Z

-        logger.error('Failed to fetch data:', e);
-        handleError(e);
+      } catch (error) {
+        logger?.log({ level: LogLevels.error, message: 'Failed to fetch data:', error });


Nit: Same as prior

LucDeCaf · 2026-05-29T14:02:48Z

-      logger.error('Failed to parse query:', e);
-      handleError(e);
+    } catch (error) {
+      logger.log({ level: LogLevels.error, message: 'Failed to parse query:', error });


Nit: Same as above

rkistner reviewed May 18, 2026

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Comment thread packages/common/src/utils/Logger.ts Outdated

simolus3 added 16 commits May 28, 2026 12:01

Remove JS logger dependency

b81ea24

Fix more logger usages

c9d13bd

Migrate web package

6b6f045

Fix multiple instances test

8017b73

Fix package build

f634158

Simplify logger design

649e9a1

Fix RNQS build

787b6bf

Fix attachments tests

9ddd48d

Fix node tests

8a2fffa

Fix web tests

822ac6c

Re-enable headless mode

55c6dc5

Fix nuxt tests

b82437f

Migrate demos

2e80dc7

Fix more demos

948de5c

Add changeset

7969a07

Rename to createConsoleLogger

6d97c35

simolus3 force-pushed the remove-js-logger branch from 2b898c3 to 6d97c35 Compare May 28, 2026 10:04

simolus3 added 3 commits May 28, 2026 14:03

Remove unused tag field

c9d51e5

Fix docs build

6ee1b43

More nuxt fixes

e733396

simolus3 marked this pull request as ready for review May 28, 2026 12:36

simolus3 requested a review from LucDeCaf May 28, 2026 12:36

LucDeCaf reviewed May 29, 2026

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Remove `js-logger` dependency#966

Remove `js-logger` dependency#966
simolus3 wants to merge 19 commits into
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simolus3 commented May 15, 2026

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changeset-bot Bot commented May 15, 2026 •

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