source: github/bin/jsshrink.sh

#!/bin/sh
JS_DIR=`dirname "$0"`/../program/js
JAR_DIR='/tmp'
LANG_IN='ECMASCRIPT3'
CLOSURE_COMPILER_URL='http://closure-compiler.googlecode.com/files/compiler-latest.zip'

do_shrink() {
        rm -f "$2"
        java -jar $JAR_DIR/compiler.jar --compilation_level=SIMPLE_OPTIMIZATIONS --js="$1" --js_output_file="$2" --language_in="$3"
}

if [ ! -d "$JS_DIR" ]; then
        echo "Directory $JS_DIR not found."
        exit 1
fi

if [ ! -w "$JAR_DIR" ]; then
        JAR_DIR=`dirname "$0"`
fi

if java -version >/dev/null 2>&1; then
        :
else
        echo "Java not found. Please ensure that the 'java' program is in your PATH."
        exit 1
fi

if [ ! -r "$JAR_DIR/compiler.jar" ]; then
        if which wget >/dev/null 2>&1 && which unzip >/dev/null 2>&1; then
                wget "$CLOSURE_COMPILER_URL" -O "/tmp/$$.zip"
        elif which curl >/dev/null 2>&1 && which unzip >/dev/null 2>&1; then
                curl "$CLOSURE_COMPILER_URL" -o "/tmp/$$.zip"
        else
                echo "Please download $CLOSURE_COMPILER_URL and extract compiler.jar to $JAR_DIR/."
                exit 1
        fi
        (cd $JAR_DIR && unzip "/tmp/$$.zip" "compiler.jar")
        rm -f "/tmp/$$.zip"
fi

# compress single file from argument
if [ $# -gt 0 ]; then
        JS_DIR=`dirname "$1"`
        JS_FILE="$1"

        if [ $# -gt 1 ]; then
                LANG_IN="$2"
        fi

        if [ ! -r "${JS_FILE}.src" ]; then
                mv "$JS_FILE" "${JS_FILE}.src"
        fi
        echo "Shrinking $JS_FILE"
        do_shrink "${JS_FILE}.src" "$JS_FILE" "$LANG_IN"
        exit
fi

# default: compress application scripts
for fn in app common googiespell list treelist; do
        if [ -r "$JS_DIR/${fn}.js.src" ]; then
                echo "$JS_DIR/${fn}.js.src already exists, not overwriting"
        else
                mv "$JS_DIR/${fn}.js" "$JS_DIR/${fn}.js.src"
        fi
        echo "Shrinking $JS_DIR/${fn}.js"
        do_shrink "$JS_DIR/${fn}.js.src" "$JS_DIR/${fn}.js" "$LANG_IN"
done