How to use the bcrypt.compare_sync function in bcrypt

app.get("/", function(req, res) {
  var salt = bcrypt.gen_salt_sync(10);
  var hash = bcrypt.encrypt_sync("B4c0/\/", salt);
  if (bcrypt.compare_sync("B4c0/\/", hash))
    res.send("hello from express");
  else
    res.send("");
});

client.query("SELECT * FROM `primarywall`.`user` WHERE `UserID` =  ?", [user], function (err, results, fields)
  {
    var success=err == null && results.length==1;
  
    if (success)
    {
      var user = JSON.parse(results[0].JSON);
      
      correctauth = bcrypt.compare_sync(pass, user.password);
    }
    else if(err)
    {
      //mysql problem
      console.error("MYSQL_ERROR: " + JSON.stringify(err));
    }
    
    callback(success, correctauth);
  });
}

adminUserModel.findOne({'username': username}, function(err, adminUserData) {
        if (err) {
            console.log('Unable to get admin user because: ' + err);
            onReady('Unable to get admin user', null);
        } else {
            if (adminUserData) {
                if (bcrypt.compare_sync(password, adminUserData.passwordHash)) {
                    adminUser.fields = adminUserData;
                    onReady(null, adminUser);
                } else {
                    onReady(null, null);
                }
            } else {
                onReady(null, null);
            }
        }
    });
};

getUser(req.body.email, function (user) {
          if (user && bcrypt.compare_sync(req.body.password, user.encrypted_password)) {
            var pt = helpers.persistence_token();
            
            user.persistence_token = pt;
            user.last_login_at = user.current_login_at;
            user.last_login_ip = user.current_login_ip;
            
            user.current_login_at = +(new Date());
            user.current_login_ip = req.connection.remoteAddress;
            saveUser(user, function () { 
              req.session.pt = pt;
              res.redirect("/");
            }, failed_authentication);
                
          } else {
            failed_authentication();
          }

redis.hgetall(req.body.email, function (err, user) {
          if (!err && user.email == req.body.email) {
            if (bcrypt.compare_sync(req.body.password, user.encrypted_password)) {
              var pt = helpers.persistence_token();
              var now = +new Date();
              var ipAddr = req.connection.remoteAddress;
              redis.hmset(req.body.email, "persistence_token", pt, "current_login_at", ""+now, "last_login_at", user.current_login_at, "last_login_ip", user.current_login_ip, "current_login_ip", ipAddr, function (err) {
                req.session.pt = req.body.email+":"+pt;
                res.redirect("/");
              });
            } else {
              res.render(__dirname+"/views/authenticate", {layout: __dirname+"/views/layout", failed: true, email: req.body.email})
            }
          } else { 
            res.render(__dirname+"/views/authenticate", {layout: __dirname+"/views/layout", failed: true, email: req.body.email})
          }
        })
      } else {

postgresql.query("select * from users where LOWER("+options["email_key"]+") = $1 and disabled_at is null and deleted_at is null", [req.body.email.toLowerCase()], function (err, result) {
          if (result.rows.length == 1) {
            var user = result.rows[0];
            if (bcrypt.compare_sync(req.body.password, user.crypted_password)) {
              var pt = helpers.persistence_token();
              var now = new Date();
              var ipAddr = req.connection.remoteAddress;
              postgresql.query("update users set persistence_token = $1, current_login_at = $2, last_login_at = $3, last_login_ip = $4, current_login_ip = $5, login_count = $6 where id = $7;", [pt, now, user.current_login_at, user.current_login_ip, ipAddr,  (user.login_count || 0) + 1, user.id ], function (err, update_res) {
                if (!err) {
                  req.session.pt = pt;
                  if (req.session.previous_url) {
                    var purl = req.session.previous_url;
                    delete req.session.previous_url;
                    res.redirect(purl);
                  } else {
                    res.redirect("/");
                  }
                } else { 
                  failed();
                }