Minification breaks certain libraries

[yogiben]

We're using a library in our Android RN app.

It works fine in dev, but breaks once minified.

Is there a way to skip minification of certain files?

[maluramichael]

Which libraries and which lines break?

[ide]

The current minifier is Uglify (may change to Babili later) so if you can figure out how to tell Uglify not to minify certain functions that would probably work for you.

[you-fail-me]

@ide Is there a way to generate a non-minified apk with react-native?

[ide]

Grep through the build process searching for minify and change whatever code is requesting minify=true in a packager URL to minify=false.

[yogiben]

In the end, we solved this by disabling mangling:

function minify(filename, code, sourceMap) {
  const minifyResult = uglify.minify(code, {
    fromString: true,
    inSourceMap: sourceMap,
    outSourceMap: true,
    mangle: false, // ADD THIS LINE
    output: {
      ascii_only: true,
      screw_ie8: true,
    },
  });

in node_modules/react-native/packager/react-packager/src/JSTransformer/worker/minify.js

We haven't found a nice way to commit this into version control yet.

[charpeni]

@facebook-github-bot label Icebox

[charpeni]

Hi there! This issue is being closed because it has been inactive for a while.

But don't worry, it will live on with ProductPains! Check out its new home: https://productpains.com/post/react-native/minification-breaks-certain-libraries

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Also, if this issue is a bug, please consider sending a PR with a fix.
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[charpeni]

@facebook-github-bot close

[facebook-github-bot]

@charpeni tells me to close this issue. If you think it should still be opened let us know why.

[ds300]

@yogiben you might be interested in patch-package for future situations like this. I use it to prevent mangling myself :-)

[coreh]

For future reference: As of September 2017 the file that needs to be patched (as described by @yogiben's instructions) has been moved to the metro-bundler module, so the path should now be:

Edit: Path changed again, see the comment below by @jackylimel

node_modules/metro-bundler/src/JSTransformer/worker/minify.js

If you're using patch-package to patch it, here's patches/metro-bundler+0.9.2.patch:

diff --git a/node_modules/metro-bundler/src/JSTransformer/worker/minify.js b/node_modules/metro-bundler/src/JSTransformer/worker/minify.js
index 3f61ce9..4927afb 100644
--- a/node_modules/metro-bundler/src/JSTransformer/worker/minify.js
+++ b/node_modules/metro-bundler/src/JSTransformer/worker/minify.js
@@ -46,10 +46,11 @@ function minify(inputCode, inputMap) {
     fromString: true,
     inSourceMap: inputMap,
     outSourceMap: true,
+    mangle: false,
     output: UGLIFY_JS_OUTPUT_OPTIONS });
 
 }
 
 module.exports = {
   noSourceMap,
-  withSourceMap };
\ No newline at end of file
+  withSourceMap };