How can i make a search Api using MEAN stack

Question

I want to make a search api and i am using the mongoose FIND this work find but not in all cases where like in lower case and uppercase, can someone please help me with a valid code that work fine. thanks in advance..

This is my controller code:

search: function(req, res, next){
    Player.find({firstName :req.params.firstName}, function(err, user){
      if(user.length === 0 ){
        res.json({message: "No Player found"});
      }else{
        res.json(user);
        next();
      }
    });
  },