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Switch from Babel to SWC for faster JavaScript transpilation #677

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Merged
merged 7 commits into from
Oct 8, 2025
+1,607 −1,391
Merged

Switch from Babel to SWC for faster JavaScript transpilation #677

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62ee4f1
Switch from Babel to SWC for faster JavaScript transpilation
justin808 Oct 6, 2025
cf7fd99
Add SWC configuration for React Fast Refresh
justin808 Oct 6, 2025
ffca3cb
Add package-lock.json to gitignore
justin808 Oct 7, 2025
f3d910d
Fix SWC config to preserve class names for Stimulus compatibility
justin808 Oct 7, 2025
ce8f58d
Add React automatic runtime to SWC config to match Babel
justin808 Oct 7, 2025
c336d81
Add loose: false to SWC config for Stimulus compatibility
justin808 Oct 8, 2025
a2654d7
Remove package-lock.json from .gitignore to detect accidental npm usage
justin808 Oct 8, 2025
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2 changes: 1 addition & 1 deletion config/shakapacker.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ default: &default
cache_path: tmp/shakapacker
webpack_compile_output: true
nested_entries: true
javascript_transpiler: babel
javascript_transpiler: swc

# Additional paths webpack should lookup modules
# ['app/assets', 'engine/foo/app/assets']
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23 changes: 23 additions & 0 deletions config/swc.config.js
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@@ -0,0 +1,23 @@
const { env } = require('shakapacker');

const customConfig = {
options: {
jsc: {
// Preserve class names for Stimulus controller discovery
keepClassNames: true,
// Use spec-compliant transforms (override Shakapacker's loose: true default)
// This is required for Stimulus controllers to work correctly
loose: false,
transform: {
react: {
// Use automatic runtime (React 17+) - no need to import React
runtime: 'automatic',
// Enable React Fast Refresh in development
refresh: env.isDevelopment && env.runningWebpackDevServer,
},
},
},
},
};

module.exports = customConfig;
3 changes: 3 additions & 0 deletions package.json
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Expand Up @@ -45,6 +45,8 @@
"@rails/actioncable": "7.0.5",
"@rescript/core": "^0.5.0",
"@rescript/react": "^0.11.0",
"@swc/core": "^1.13.5",
"ajv": "^8.17.1",
Comment on lines +48 to +49
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⚠️ Potential issue | 🔴 Critical

🧩 Analysis chain

Verify that the SWC dependency versions are current.

The versions of SWC-related packages may be outdated. Please ensure you're using the latest stable versions for optimal performance and security.

Since my knowledge may be outdated, please verify the current versions:

Also applies to: 101-101

🌐 Web query:

What are the latest stable versions of @swc/core and swc-loader packages?

💡 Result:

@swc/core — 1.13.1 (latest stable, published Jul 19, 2025). [1]
swc-loader — 0.2.6 (latest stable). [2]

Sources:
[1] Snyk package page for @swc/core.
[2] npm package page for swc-loader.

Update @swc/core to latest stable (1.13.1)
The declared "^1.13.5" isn’t published; change it to "^1.13.1".

🤖 Prompt for AI Agents 
package.json around lines 48-49: the dependency entry for "@swc/core" is set to
an unpublished "^1.13.5"; change it to the published latest stable "^1.13.1",
update package.json accordingly, then run your package manager (npm install or
yarn install) to update node_modules and lockfile (package-lock.json or
yarn.lock) and verify the project builds/tests pass.

"autoprefixer": "^10.4.14",
"axios": "^0.21.1",
"babel-loader": "^9.1.2",
Expand Down Expand Up @@ -96,6 +98,7 @@
"shakapacker": "9.0.0-beta.8",
"stimulus": "^3.0.1",
"style-loader": "^3.3.1",
"swc-loader": "^0.2.6",
"tailwindcss": "^3.3.3",
"terser-webpack-plugin": "5",
"turbolinks": "^5.2.0",
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