title: Gulp: Why my 'clean' task don't work using the callback function?
body: <p>My gulp file is above:</p>
  
  <pre><code>var gulp = require('gulp');
  
  var concat = require('gulp-concat');
  var uglify = require('gulp-uglify');
  var del = require('del');
  
  gulp.task('clean', function(cb) {
      del(['dist/*.js'], cb);
  });
  </code></pre>
  
  <p>When I run 'gulp clean', my output is:</p>
  
  <pre><code>[12:45:05] Using gulpfile
  
  [12:45:05] Starting 'clean'...
  </code></pre>
  
  <p>The command delete the files of dist folder.</p>
  
  <p>If I remove the callback function, the result is:</p>
  
  <pre><code>gulp.task('clean', function() {
  
      del(['dist/*.js']);
  
  });
  
  [12:54:07] Using gulpfile 
  
  [12:54:07] Starting 'clean'...
  
  [12:54:07] Finished 'clean' after 4.
  </code></pre>
  
  <p>What I'm doing wrong with the callback function?</p>
  
  <p>Regards.</p>