exports.postHome=(req,res,next)=>{
    const lattitude=req.body.lattitude;
    const longitude= req.body.longitude;
    req.session.lat=lattitude;  //setting session
    req.session.lang=longitude; 
    req.session.save(err=>{      
    if(!err)
    {
    console.log("inpost");
    console.log(lattitude);
    console.log(longitude);
    res.redirect('/');
    }
    })
    
  }

如果req.session.save已同步，则其工作正常.

if req.session.save is synchronized its working correctly.