The debug-js Element
From Documentation
Syntax:
<debug-js>true|false</debug-js>
[Default: false]
It specifies whether to debug JavaScript files. By default, it is false and the compressed version of JavaScript files will be loaded. They are hard to read and debug, though the footprint is much smaller.
To debug JavaScript files, you can specify it to true. Then, the original uncompressed JavaScript files will be loaded instead.