A few changes can be made to reduce the footprint of Rhino for embeddings where space is at a premium. On a recent build, the length of js.jar was 603,127 bytes corresponding to 1,171,708 bytes of all uncompressed Rhino classes with debug information included. With various changes js.jar size can be reduced to 204,689 bytes corresponding to 424,774 bytes of uncompressed classes.
Tools
Most embeddings won't need any of the classes in
org.mozilla.javascript.tools or any of its sub-packages.
Optimizer
It is possible to run Rhino with interpreter mode only, allowing you to remove code for classfile generation that include all the classes from <tt>org.mozilla.javascript.optimizer</tt> package.
JavaAdapter
Implementing the JavaAdapter functionality requires the ability to
generate classes on the fly. Removing
org.mozilla.javascript.JavaAdapter will disable this
functionality, but Rhino will otherwise run correctly.
Class generation library
If you do not include Optimizer or JavaAdapter, nor do you use
PolicySecurityController then you do not need Rhino library for class
file generation and you can remove all the classes from in
org.mozilla.classfile package.
Regular Expressions
The package org.mozilla.javascript.regexp can be
removed. Rhino will continue to run, although it will not be able to
execute any regular expression matches. This change saves 47,984
bytes of class files.
Debug information
Debug information in Rhino classes consumes about 25% of code size and if you can live without that, you can recompile Rhino to remove it.
smalljs.jar
Ant build script in Rhino supports smalljar target that will generate smalljs.jar that does not include Tools, Optimizer, JavaAdapter and Class generation library, Regular Expressions, E4X implementataion and deprecated files. To build such minimalist jar without debug information, run the following command from the top directory of Rhino distribution:
ant clean ant -Ddebug=off -Dno-regexp=true -Dno-e4x=true smalljar
If you omit -Dno-regexp=true, then the resulting
smalljs.jar will include Regular Expression support. Similarly
omitting -Dno-e4x=true results in smalljs.jar
that includes runtime support for E4X.