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Question

我在文件中有一个对象，希望能够要求该文件，然后随心所欲地创建对象的新实例，但我遇到了麻烦。这看起来非常基本，我错过了什么。

hat.js

function Hat(owner) {
    this.owner = owner;
}
Hat.prototype.tip = function() {
    console.log("and he (" + owner + ") tipped his hat, just like this");
}
exports.Hat = Hat;

节点终端

尝试1

> require('./hat.js');
> var mighty_duck = new Hat('Emilio');
  ReferenceError: Hat is not defined

尝试2

> var Hat = require('./hat.js');
> var mighty_duck = new Hat('Emilio');
  { owner: 'Emilio' }
> mighty_duck.tip();
  TypeError: Object #<Hat> has no method 'tip'

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我，最不幸的是，遗漏了最重要的问题。我试图使用

的事实

util.inherits(Hat, EventEmitter);

所以我的hat.js实际上是

function Hat(owner) {
    this.owner = owner;
}
Hat.prototype.tip = function() {
    console.log("and he (" + owner + ") tipped his hat, just like this");
}
util.inherits(Hat, EventEmitter);
exports.Hat = Hat;

这是一个问题，因为，显然在开始扩展原型之前让inherits调用非常重要。修复很简单，将inherits调用移动几行

function Hat(owner) { this.owner = owner; } util.inherits(Hat, EventEmitter); Hat.prototype.tip = function() { console.log("and he (" + owner + ") tipped his hat, just like this"); } exports.Hat = Hat;

Answer 1

看看这里：http://openmymind.net/2012/2/3/Node-Require-and-Exports/

您可以尝试这样做：

function Hat(owner) {
    this.owner = owner;
}
Hat.prototype.tip = function() {
    console.log("and he (" + this.owner + ") tipped his hat, just like this");
}
module.exports = Hat;

然后......像这样：

var hat = require('./hat.js');
var mighty_duck = new hat('Emilio');
mighty_duck.tip()

Answer 2

你正在做你的要求错误：

var Hat = require('./hat.js').Hat;

是你想要的。执行exports.Hat = Hat;时，您正在导出一个exports的对象（Hat）。因此，当您需要'./hat.js'时，您将获得该对象，并需要访问Hat属性。

来自节点repl：

> require('./hat.js');
{ Hat: [Function: Hat] }
> require('./hat.js').Hat;
[Function: Hat]
> var Hat = require('./hat.js').Hat;
undefined
> var mighty_duck = new Hat('Emilio');
undefined
> mighty_duck.tip();
and he (Emilio) tipped his hat, just like this

当然，由于您在owner中说this.owner而不是tip()，导致错误，但在我更改之后它运行良好：）

如果你想做的话

var Hat = require('./hat.js'),
    hat = new Hat('Emilio');

然后将导出更改为：

module.exports = exports = Hat;

它有效：

> require('./hat.js');
[Function: Hat]
> var Hat = require('./hat.js');
undefined
> var hat = new Hat('Emilio');
undefined
> hat.tip();
and he (Emilio) tipped his hat, just like this

编辑清理并继承自EventEmitter：

var util = require('util'),
    events = require('events');

var Hat = exports.Hat = function(owner) {
    events.EventEmitter.call(this);
    this.owner = owner;
}

util.inherits(Hat, events.EventEmitter);

Hat.prototype.tip = function() {
    console.log("and he (" + this.owner + ") tipped his hat, just like this");
}

如何在node.js中导出添加了原型方法的对象

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2 个答案: