How do I concatenate JavaScript files into one file?

To copy without EOF use binary mode:

copy /B *.js compiled.js /Y

If the resulting file still has EOFs, that might have come from one of original files, it can be fixed by this variant:

copy /A *.js compiled.js /B /Y

/A removes trailing EOFs from original files if any and /B prevents appending EOF to the resulting file. If an EOF is not at the end, the source file will be truncated at it. The order of switches is important. If you write

copy /A *.js /B compiled.js /Y  

- EOFs in source files won't be removed but still resulting EOF won't be appended.

Try it yourself, thats where I get it. DOS commands are weird.

I recommend using Apache Ant and YUI Compressor.

http://ant.apache.org/

http://yui.github.com/yuicompressor/

Put something like this in the Ant build xml. It will create two files, application.js and application-min.js.

<target name="concatenate" description="Concatenate all js files">
    <concat destfile="build/application.js">
        <fileset dir="src/js" includes="*.js" />
    </concat>
</target>

<target name="compress" depends="concatenate" description="Compress application.js to application-min.js">
    <apply executable="java" parallel="false">
        <filelist dir="build" files="application.js" />
        <arg line="-jar" />
        <arg path="path/to/yuicompressor-2.4.2.jar" />
        <srcfile />
        <arg line="-o" />
        <mapper type="glob" from="*.js" to="build/*-min.js" />
        <targetfile />
    </apply>
</target>