How can I skip a grunt task if a directory is empty

Question

I'm using grunt-contrib's concat and uglify modules to process some javascript. Currently if src/js/ is empty, they will still create an (empty) concat'd file, along with the minified version and a source map.

I want to task to detect if the src/js/ folder is empty before proceeding, and if it is, then the task should skip (not fail). Any ideas how to do this?

Answer 1

The solution may not be the prettiest, but could give you an idea. You'll need to run something like npm install --save-dev glob first. This is based on part of the Milkshake project you mentioned.

grunt.registerTask('build_js', function(){
  // get first task's `src` config property and see
  // if any file matches the glob pattern
  if (grunt.config('concat').js.src.some(function(src){
    return require('glob').sync(src).length;
  })) {
    // if so, run the task chain
    grunt.task.run([
        'trimtrailingspaces:js'
      , 'concat:js'
      , 'uglify:yomama'
    ]);
  }
});

A gist for comparison: https://gist.github.com/kosmotaur/61bff2bc807b28a9fcfa