title: Grunt concat + uglify with sourcemaps
body: <p>I use concat to merge JS files into one file and uglify to minimize the JavaScript. How can I create a sourcemaps file that uses the source JS files? </p>
  
  <p>My current gruntfile:</p>
  
  <pre class="lang-js prettyprint-override"><code>concat: {
      options: {
          // define a string to put between each file in the concatenated output
          separator: ';'
      },
      dist: {
          // the files to concatenate
          src: ['&lt;%= config.src %&gt;/js/**/*.js'],
          // the location of the resulting JS file
           dest: '&lt;%= config.dist %&gt;/js/main.js'
      }
  },
  
  uglify: {
      dist: {
          files: {
              '&lt;%= config.dist %&gt;/js/main.min.js': ['&lt;%= concat.dist.dest %&gt;']
          }
      }
  },
  </code></pre>