Source rebuild (Node 24.21.0 was tested)
1. mkdir build/audio
2. tar -xf sources/lamejs-1.2.1.tgz -C build/audio
3. npm ci --prefix tooling --ignore-scripts --no-audit --no-fund
4. node rebuild-audio.mjs
Output: build/audio/rebuilt/lame.min.js (browser global lamejs.Mp3Encoder and WavHeader).
Browserify 17.0.1 and Terser 5.44.0 and transitive tool dependencies are locked.
General-purpose tool dependencies are fetched by npm ci; this kit does not need Java,
Closure compiler.jar, shell grep/sed or the undocumented upstream tool versions.
Build recipe was changed, codec algorithms were not. Old minified artifact byte identity
is NOT claimed. Repeat-build bytes and 24 original/rebuilt MP3 streams were checked.
Original source remains under LGPL; retain LICENSE, licenses/GPL-3.0.txt and LGPL-3.0.txt.
Replace the local application's vendor/lame.min.js, restart its local server, clear cache.

Original corresponding source: sources/lamejs-1.2.1.tgz
Rebuild kit: sources/lamejs-source-build-kit.zip
Actual same-origin downloads are available at the links on licenses/index.html.
The source archive includes Java/JS sources, not only a minified distribution.
Library credit: https://github.com/zhuker/lamejs and https://lame.sourceforge.io/
No warranty; retain third-party license notices.