grunt-hash.js

uglify: {
  production: {
    options: {
      report: 'min'
    },
    files: [{
      expand: true,
      cwd: '<%= dir.tempJS %>/',
      src: '*.js',
      dest: '<%= dir.publicJS %>',
      rename: function( dest, srcName, options ){
        // Calculate md5 hash
        var
          fs = require('fs'),
          crypto = require('crypto'),
          md5 = crypto.createHash('md5'),
          pathToFile = grunt.template.process( options.cwd + srcName ),
          buffer = fs.readFileSync( pathToFile ),
          fileName = srcName.replace('.js', '');

        md5.update( buffer );
        var md5Hash = md5.digest('hex');

        return dest + '/' + fileName + '.min.' + md5Hash + '.js';
      }
    }]
  }
}