Javascript Node.js v6.2.0 类扩展不是函数错误？
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Node.js v6.2.0 class extends is not a function error?
提问by James111
So I'm trying to extend a class in node js and the compiler keeps returning the following error:
所以我试图在 node js 中扩展一个类，编译器不断返回以下错误：
TypeError: Class extends value #<Object> is not a function or null
I checked that I was exporting the class correctly and I am, any ideas? I'll post my code below:
我检查了我是否正确导出了课程，我是，有什么想法吗？我将在下面发布我的代码：
/handler/venue.js:
/handler/venue.js：
var VenueViews = require('../views/venue'); // If I remove this the error will dissapear (as expected)
class Venue {
constructor(data) {
this.setDataHere = data;
}
main () {
var View = new VenueViews(); // This doesn't run
}
}
module.exports = Venue;
/views/venue.js:
/views/venue.js：
var Venue = require('../handlers/venue');
console.log (Venue) // This returns {} ???
class VenueViews extends Venue {
constructor() {
super();
}
}
module.exports = VenueViews;
I know that node supports these es6 features, so I'm unsure why they aren't working?
我知道 node 支持这些es6 features，所以我不确定为什么它们不起作用？
Edit:
编辑：
I'm not sure if this is suppose to happen but, when I log my Venuerequire it returns an empty object {}.
我不确定这是否会发生，但是，当我记录我的Venuerequire 时，它返回一个空对象{}。
console.log (Venue) // This returns {} ???
回答by James111
So it turns out I had a circular reference in my code, where I was importingthe class that was extending, into the class that itself was extending (tongue twister :P).
所以事实证明我在我的代码中有一个循环引用，我是importing正在扩展的类，到它本身正在扩展的类中（绕口令：P）。
The obvious fix was to simply remove the extendsreference and find another way of doing what I was trying to achieve. In my case it was passing the Venueclass properties down into the VenueViewsconstructor.
显而易见的解决方法是简单地删除extends引用并找到另一种方式来做我想要实现的目标。在我的情况下，它将Venue类属性传递给VenueViews构造函数。
E.g var x = VenueViews(this)
例如 var x = VenueViews(this)
回答by Blaskovicz
In my instance, it was the same issue as @James111 was experiencing (circular import) due to a factory pattern I was trying to set up in Typescript. My fix was to do move the code into files, similar to the following:
在我的例子中，由于我试图在 Typescript 中设置工厂模式，这与 @James111 遇到的问题（循环导入）相同。我的解决方法是将代码移动到文件中，类似于以下内容：
// ./src/interface.ts
import { ConcreteClass } from './concrete';
export interface BaseInterface {
someFunction(): any;
}
export class Factory {
static build(): BaseInterface {
return new ConcreteClass();
}
}
// ./src/base.ts
import { BaseInterface } from './interface';
class BaseClass implements BaseInterface {
someFunction(): any {
return true;
}
}
// ./src/concrete.ts
import { BaseClass } from './base';
export class ConcreteClass extends BaseClass {
someFunction(): any {
return false;
}
}
