Uglify or concat a JavaScript file conditionallly

I have a "Lib" folder and an "App" folder in my Scripts folder.

The Lib folder contains third-party library JavaScript files. Some of these are minified without the original sources, others we have the original sources for.

The App folder contains all of our own JavaScript files, all of which are not minified.

I'm new to Grunt, but I have a gruntfile which does the following:

• Uglifies all the JavaScript files in the Lib folder and produces minified versions with sourcemaps.
• Uglifies all the JavaScript files in the App folder and produces minified versions with sourcemaps.

Obvious problem: some of the files in the Lib folder are minified, so minifying them again/generating source maps is a bad idea and can fail for various reasons.

My solution: I run Uglify only on .js files in the Lib folder into lib-unmin.min.js. I then concatenate all the already-minified files into a lib-min.min.js file, then I concatenate both those files together to get lib.min.js.

The new problem

What if I can't concatenate the already minified scripts to the end of the other minified scripts without it breaking?

I have a dependency issue like this:

• scripts/lib/a.js (required for b to run)
• scripts/lib/b.min.js (required for c to run)
• scripts/lib/c.js (required for the App scripts to run)

If I have an array of these file paths in my gruntfile, in that order, what's the easiest way of uglifying/concatenating all the files into a single minified JavaScript file in that order, making sure we don't attempt to minify the minified file?

What do other developers do in similar situations?

I like to concatenate the files and then uglify all of them together. This way, UglifyJS makes sure there aren't duplicate variable values overriding each other when it compresses the variable names.

You can bundle as many files as you want in the concatenations. Make different concatenation groups to uglify together and maintain the 'first, second, third, ...' order like this:

module.exports = function(grunt) {
  grunt.initConfig({
    pkg: grunt.file.readJSON('package.json'),
    uglify: {
      app: {
        options: {
          sourceMap: true,
          sourceMapName: 'build/maps/map.map'
        },
        files: {
          'build/app.min.js': ['build/js/app-first-unmin.js', 'build/js/app-second-min.js', 'build/js/app-third-unmin.js']
        }
      }
    },

    concat: {
      options: {
        separator: ';'
      },
      firstUnminified: {
        src: [
          'lib/underscore.js'
        ],
        dest: 'build/js/app-first-unmin.js'
      },
      secondMinified: {
        src: [
          'lib/moment.min.js'
        ],
        dest: 'build/js/app-second-min.js'
      },
      thirdUnminified: {
        src: [
          'lib/favico.js'
        ],
        dest: 'build/js/app-third-unmin.js'
      }
    },
  });

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

  grunt.registerTask('default', ['concat:firstUnminified', 'concat:secondMinified', 'concat:thirdUnminified','uglify']);
};