node.js中的类方法

Question

我一直在尝试用lastOne，findOneOrCreate等方法为passport.js编写用户模块的最后一小时，但无法正确使用。

user.js的

var User = function(db) {
  this.db = db;
}

User.prototype.findOne(email, password, fn) {
  // some code here
}

module.exports = exports = User;

app.js

User = require('./lib/User')(db);
User.findOne(email, pw, callback);

我经历过几十个错误

TypeError: object is not a function

要么

TypeError: Object function () {
  function User(db) {
    console.log(db);
  }
} has no method 'findOne'

如何在不创建User对象/实例的情况下使用这些函数创建合适的模块？

更新

我讨论了提出的解决方案：

var db;
function User(db) {
  this.db = db;
}
User.prototype.init = function(db) {
  return new User(db);
}
User.prototype.findOne = function(profile, fn) {}
module.exports = User;

没运气。

TypeError: Object function User(db) {
  this.db = db;
} has no method 'init'

Answer 1

这里有几件事情，我已经更正了你的源代码并添加了注释来解释：

LIB / user.js的

// much more concise declaration
function User(db) {
    this.db = db;
}

// You need to assign a new function here
User.prototype.findOne = function (email, password, fn) {
    // some code here
}

// no need to overwrite `exports` ... since you're replacing `module.exports` itself
module.exports = User;

app.js

// don't forget `var`
// also don't call the require as a function, it's the class "declaration" you use to create new instances
var User = require('./lib/User');

// create a new instance of the user "class"
var user = new User(db);

// call findOne as an instance method
user.findOne(email, pw, callback);

Answer 2

您需要在某个时刻new User(db) 。

你可以制作一个init方法

exports.init = function(db){
  return new User(db)
}

然后从你的代码：

var User = require(...).init(db);