how to config grunt.js to minify files separately

Had the same problem and found a solution that would automatically minify all my scripts separately:

uglify: {
      build: {
        files: [{
            expand: true,
            src: '**/*.js',
            dest: 'build/scripts',
            cwd: 'app/scripts'
        }]
      }
    }

In grunt 0.4 you can specify multiple dest/src pairs like this:

uglify: {
    dist: {
        files: {
            'dist/main.js': 'src/main.js',
            'dist/widget.js': 'src/widget.js'
        }
    }
}

Or you can use expandMapping, like this:

min: {
    files: grunt.file.expandMapping(['path/*.js', 'path2/*.js'], 'destination/', {
        rename: function(destBase, destPath) {
            return destBase+destPath.replace('.js', '.min.js');
        }
    })
}

And the output:

path/test.js => destination/path/test.min.js
path2/foo.js => destination/path2/foo.min.js

This below gruntjs works for me for creating minified files for all the js files under a dir

module.exports = function(grunt) {

  // Project configuration.
  grunt.initConfig({
    pkg: grunt.file.readJSON('package.json'),
    uglify: {
    build: {
        files: [{
            expand: true,
            src: '**/*.js',
            dest: 'build/scripts',
            cwd: 'public_html/app',
        ext: '.min.js'
        }]
      }
    }
  });

  // Load the plugin that provides the "uglify" task.
  grunt.loadNpmTasks('grunt-contrib-uglify');

  // Default task(s).
  grunt.registerTask('default', ['uglify']);

};

From the grunt docs for min:

This task is a multi task, meaning that grunt will automatically iterate over all min targets if a target is not specified.

So you can do this:

  min: {
    min_a: {
       src:  'a.js',
       dest: 'a.min.js'
    },
    min_b: {
       src:  'b.js',
       dest: 'b.min.js'
    },
    min_c: {
       src:  'c.js',
       dest: 'c.min.js'
 }

There's nothing special about the name 'dist' for these tasks.

Use the ext option to name the files .min.js instead of .js

uglify: {
      build: {
        files: [{
            expand: true,
            src: '**/*.js',
            dest: 'build/scripts',
            cwd: 'app/scripts',
            ext: '.min.js'
        }]
      }
    }

For explicitly export some files into separate output files (in this case all.min.js and all.jquery.js) use:

uglify: {
  js: {
    files : {
        'js/all.min.js' : [
          'js/modernizr.js',
          'js/vendor/modernizr-2.6.2-respond-1.1.0.min.js',
          'js/bootstrap.min.js',
          'js/main.js',
          'js/ZeroClipboard.min.js',
          'js/bootstrap-datepicker/bootstrap-datepicker.js'
        ],

        'js/all.jquery.js' : [
          'js/vendor/jquery-1.9.1.js',
          'js/vendor/jquery-migrate-1.2.1.js',
          'js/vendor/jquery-ui.js'
        ]

    }
  },
  options: {
    banner: '\n/*! <%= pkg.name %> <%= grunt.template.today("dd-mm-yyyy") %> */\n',
    preserveComments: 'some',
    report: 'min'
  }
},

I like to keep the original files and also create uglified ones:

uglify: {
  dist: {
    files: [{
      expand: true,
      src: '**/*.js',
      dest: 'destdir',
      cwd: 'srcdir',
      rename: function(dest, src) { return dest + '/' + src.replace('.js', '.min.js'); }
    }]
  }
},

You also can use copy and grunt-mindirect.

copy: {
  dist: {
    src: 'a.js',
    dest: 'a.min.js'
  }
},
minidirect: {
  all: 'js/min/*.min.js'
}

This should work.

I guess it only matters for watch tasks.

In grunt 0.4 you can do this

  var filesA = 'a.js', filesB = 'b.js', filesC = 'c.js';

  ...

  min: {
      min_a: {
         src:  filesA,
         dest: 'a.min.js'
      },
      min_b: {
         src:  filesB,
         dest: 'b.min.js'
      },
      min_c: {
         src:  filesC,
         dest: 'c.min.js'
  }

  watch: {
      min_a: {
         files:  filesA,
         tasks: ['min:min_a']
      },
      min_b: {
         files:  filesB,
         tasks: ['min:min_b']
      },
      min_c: {
         files:  filesC,
         tasks: ['min:min_c']
      }
  }

After that just start grunt watch and all will be fine automagically.

In an intention to help others who come to this page in future -

I came across a video which explains on how to minify JS files using Grunt JS here: https://www.youtube.com/watch?v=Gkv7pA0PMJQ

The source code is made available here: http://www.techcbt.com/Post/359/Grunt-JS/how-to-minify-uglify-javascript-files-using-grunt-js

Just in case, if the above links are not working:

1. You can minify all javascript files and combine/concat into one file using the following script:

    module.exports = function(grunt){
	grunt.loadNpmTasks('grunt-contrib-uglify');	
	
	grunt.initConfig({
		pkg: grunt.file.readJSON('package.json'),

		uglify:{
			t1:{
				files:{
					'dest/all.min.js': ['src/app.js', 'src/one.js', 'src/t/two.js']
				}
			}
		}
	});	
};

2. If you would like to have source maps also generated, you can enable "sourceMap" option as follows:

    module.exports = function(grunt){
	grunt.loadNpmTasks('grunt-contrib-uglify');	

	grunt.initConfig({
		pkg: grunt.file.readJSON('package.json'),

		uglify:{
			t1:{
				options : {
        			sourceMap : true,
      			},
				files:{
					'dest/all.min.js': ['src/app.js', 'src/one.js', 'src/t/two.js']
				}
			}
		}
	});	
};

3. In order to retain entire folder structure while minifying JS files, you can use the following script:

    module.exports = function(grunt){
	grunt.loadNpmTasks('grunt-contrib-uglify');	

	grunt.initConfig({
		pkg: grunt.file.readJSON('package.json'),

		uglify:{
			t1:{
				files: [{
					cwd: 'src/',
               		src: '**/*.js',  
               		dest: 'dest/',    
               		expand: true,    
               		flatten: false,
               		ext: '.min.js'
           		}]
			}
		}
	});	
};