var req = { body: {} };

req.body.learninglanguages = 'test,this,another,that,here,forever';

req.body.spokenlanguages = 'test2,this2,another2,that2,here2,forever2';

req.body.country = 'USA';

req.body.commethod = 'whatever';

​

var q = {}; // declare the query object

  q['$and']=[]; // filter the search by any criteria given by the user

  if((req.body.learninglanguages).length > 0){ // if the criteria has a value or values

    q["$and"].push({ learningLanguages: {$in: req.body.learninglanguages.split(",") }}); // add to the query object

  }

  if((req.body.spokenlanguages).length > 0){

    q["$and"].push({ spokenLanguages: {$in: req.body.spokenlanguages.split(",") }});

  }

  if((req.body.country).length > 0){

    q["$and"].push({ country: {$in: req.body.country.split(",") }});

  }

  if((req.body.commethod).length > 0){

    q["$and"].push({ comMethod: {$in: req.body.commethod.split(",") }});

  }

​

console.log(q);