Creating a script to use Google Closure for multiple javascript files

Question

I need to use the Google Closure compiler.jar to minify a huge project I am working on. I have multiple js files that I want to compile into a single game.min.js file. I know I can use the following:

java -jar compiler.jar --js file1.js --js file2.js --js etc, etc --js_output_file game.min.js

...but I have a LOT of files and as I understand it Closure doesn't have support for adding a directory and finding all the *.js files residing under that directory. My fumbling google searches are not giving me any tools that I can use for the job (or nothing that works at any rate).

Has anyone out there found / used / written a script that loops through a directory and spits out all the .js files into a single minified file? I am hopeless with php, python, etc, so any help greatly appreciated.

Answer 1

You can use ant to automate the use of the closure compile r.

I do it in two separate steps, concatenation then compilation :

<concat destfile="src/somepath/app.concat.js">
    <filelist dir="src/somepath">
        <file name="a.js" />
        <file name="b.js" />
        <file name="c.js" />
        <file name="d.js" />
    </filelist>
</concat>

<jscomp compilationLevel="simple" warning="quiet" debug="false" output="src/app.min.js">
    <sources dir="src/somepath">
        <file name="app.concat.js" />
    </sources>
</jscomp>

Be careful that the order of the files is important. That's why you can't simply pass a fileset to the jscomp task.

Answer 2

You can also use wildcards when specifying files. You could change your example to:

java -jar compiler.jar --js *.js --js_output_file game.min.js

This should combine all of the .js files in your current working directory into the output file you've specified.

Answer 3

You should concatenate all your source files before you apply Google Closure compiler.

For all related tasks you could use Ant build tool. Also, there is a great Grunt.js project, which is more convenient for JS. There are grunt-contrib-concat and grunt-shell npm modules for Grunt.js, the first is for concatenation, the other is for running console commands.

Your Gruntfile.js could look like this:

module.exports = function(grunt) {
    // Project configuration.
    grunt.initConfig({
        concat: {
            js: {
                src: ['src/js/*.js'],
                dest: 'dist/pre-build.js'
            }
        },

        shell: {
            optimize: {
                command: 'google closure compiler command here',
                stdout: true
            }
        }
    });

    grunt.loadNpmTasks('grunt-shell');
    grunt.loadNpmTasks('grunt-contrib-concat');

    // Default task.
    grunt.registerTask('default', ['concat', 'shell:optimize']);
};