Find unused package in your nodeJS app with gulp task.

gulpfile.js

var depcheck = require('depcheck');
var path = require('path');

gulp.task('unusedPackages', function() {
  var options = {
    withoutDev: false,
    ignoreDirs: ['lib', 'locales', 'logs', 'public'],
    ignoreMatches: ['gulp-*']
  };

  var root = path.resolve('.');

  depcheck(root, options, function(unused) {
    if(unused.dependencies.length > 0 || unused.devDependencies.length > 0) {
      console.log('=> Some packages are useless and should be removed');
      if(unused.dependencies.length > 0) {
        console.log("- " + unused.dependencies.join("\n - "));
      }
      if(unused.devDependencies.length > 0) {
        console.log("- (dev) " + unused.devDependencies.join("\n - "));
      }
    }
  });
});