How to use

diff

function

in

Array

missingKeys(){
   if(!this.selectedLang) return [];
   
   let selectedKeys = Object.keys(this.selectedLang) || [];
   let scannedKeys = this.scannedKeys || [];
   
   return scannedKeys.diff(selectedKeys);
  }

extraKeys(){
   let selectedKeys = Object.keys(this.selectedLang) || [];
   let scannedKeys = this.scannedKeys || [];
   
   return selectedKeys.diff(scannedKeys);
  }

router.get(/^\/related_terms\/([^\/]+)$/, function(req, resp) {
    var tags = req.params[0].split(" ");
    var query = "SELECT `tag` FROM `product_tags`";
    app.db.all(query, function(err, res) {
      if (!!err) return resp.status(501).end();
      if (!res) return resp.status(404).end();
      var terms = [];
      res.forEach(function(data) { terms.push(data.tag); });
      Array.prototype.diff = function(a) {
        return this.filter(function(i) {return a.indexOf(i) < 0;});
      };
      terms = terms.diff(tags);
      resp.status(200).json(app.limitResponse(req, { data: terms }));
    });
  });

router.get(/^\/related_queries\/([^\/]+)$/, function(req, resp) {
    var query = "SELECT `tag` FROM `product_tags`";
    app.db.all(query, function(err, res) {
      if (!!err) return resp.status(501).end();
      if (!res) return resp.status(404).end();
      var terms = [];
      res.forEach(function(data) { terms.push(data.tag); });
      var queries = [];
      for (var i=0; i<=(Math.random()*1000 % 10); i++) {
        var query = [];
        for (var j=0; j<=(Math.random()*1000 % Math.max(terms.length, 3)); j++) {
          query.push(terms[j]);
        }
        queries.push(query.join(" "));
      }
      Array.prototype.diff = function(a) {
        return this.filter(function(i) {return a == i;});
      };
      queries = queries.diff(req.query["q"]);
      resp.status(200).json(app.limitResponse(req, { data: queries }));
    });
  });