Added support for source maps

[soluml]

Added source map support for this plugin, also added documentation.

[gmarty]

Thanks Benjamin.
Can you explain why do you need a special treatment for generating source map? The setting in options are passed directly to Closure Compiler interns.
What didn't work with:

grunt.initConfig({
  'closure-compiler': {
    frontend: {
      closurePath: '/src/to/closure-compiler',
      js: 'static/src/frontend.js',
      options: {
        create_source_map: 'src.map',
        source_map_format: 'V3'
      }
    }
  }
});

[soluml]

Thanks for your response Guillaume, I totally missed that in the documentation. Creating the maps with the options object works great! Go ahead and ignore this request.

I've modified my code to only include the "sourceMapUrl" option, which appends the sourceMapUrl comment to the end of the generated JS file which associates the two together. I have no idea why this isn't built into Closure Compiler by default, but I wasn't able to find any documentation on a flag to turn this on. I'm working in a Jenkins environment where hand editing files is a no go and this way we don't have to manage a bunch of X-SourceMap headers on the files.

I'll add a new pull request for just this code. Thanks!

[soluml]

Added a new pull request for just the sourceMapUrl feature: #43

Thanks again for pointing this out Guillaume!

[evenicoulddoit]

I'm using this along with the grunt watch plugin and it's adding the map to my root directory. IMO it should go into the same folder as the compiled JS.

[evenicoulddoit]

This isn't checking for "truthy", you should use if data.sourceMapUrl === true

[ChadKillingsworth]

I have no idea why this isn't built into Closure Compiler by default

I'm a Closure-compiler project maintainer. You do not need any special options - you should use the output_wrapper option that already exists on the compiler to add the source map url comment. See https://github.com/google/closure-compiler/wiki/FAQ#source-maps-and-sourcemappingurl