Async write after select Pouchdb

I'm trying to check if an element exist before inserting it in my bdd. I have to do this in order to (in the future) modify this existing element.

I'm using PouchDb and PouchDb-find Node 6.9.1 (please don't judge me)

Actually i'm doing this :

for(var i = 0; i < 10;i++ ){
    (function(_count, _pdb){
      var count = _count;
      var db = _pdb;
      db.find({
        selector: {numeroCandidat: parseInt(results[count].no_apb)}
      }).then((result) => {
        if(result.docs.length != 0){
          console.log("l'étudiant existe");
        }else{
          console.log("l'étudiant n'existe pas");

          var etudiant = {
            "numeroCandidat": results[count].no_apb,
            "nom": results[count].nom,
            "numeroGroupe": "gr" + results[count].groupe,
            "filiere": results[count].libelle,
          };

          db.post(etudiant).then((response) =>{
            // handle response
            console.log("STUDENT CREATED");
          }).catch(function (err) {
            console.log(err);
          });
        }
      }).catch(function (err) {
      });
    })(i, this.pdb);
  };

But the problem is : Due to the asynchronous version of my select query... if an element extis two tims it appends that the second select occured BEFORE the insertion of the first element.. and I have this element two times in my database.... don't know how to deal with this one guys..

Thanks a lot for you help.

via Stephane Karagulmez