problem description

create a student Schame, with mongoose but report an error at run time, the error is in the Schema; of the third line

TypeError: schema is not a constructor

looked at the code did not find a mistake, please help to have a look, thank you!

related codes

var mongoose = require("mongoose"),
    Schema = mongoose.Schema;
const courseInf = new Schema({
    teacher:String,
    courseName:String
});
const student = new Schema({
    name:String,                //
    class:String,                //
    stunum:String,                //
    oldpassword:String,           //
    newpassword:String,           //
    phonenum:String,              //
    course:[courseInf]           //
});

module.exports.stu = mongoose.model("student",student);