class 的构造函数在模块中 require 之后未定义

Question

我正在尝试在 Node.js 中导入一个 class，这样我就可以在我的主要函数中创建它的实例但是当尝试这样做时我得到错误 Epicenter is not a constructor 我已经尝试在我的 class 之前使用 export 并尝试将“type”：“module”添加到我的 package.json 但似乎什么都做不到区别，我也试过使用 import 但这也没有解决它:(

我的节点版本是12.17.0，希望有人能出出主意，不胜感激

这是我的主要模块

const Epicenter = require("./EpicenterClass.js");


// makes a board where nodes are assigned randomly to slots 

const makeboard = (nodes, randomLimit) =>{
var map = [[]];
var nodeCount = 0;
map.length = Math.floor(Math.random(10)+randomLimit);

console.log('making board',map,nodeCount,map.length)
for (const xloc of map) {
    Math.floor(Math.random(10)+1) > xloc && nodeCount < nodes ? map[xloc] = new Epicenter(1,2,3,4) 
    :
     map[xloc] = '';
    nodeCount++

    for (const yloc of map[xloc]) {
    Math.floor(Math.random(10)+1) > yloc && nodeCount < nodes ? map[yloc] = new Epicenter(1,2,3,4) 
    :
     map[yloc] = '';
    nodeCount++
      }     
  }

console.log(`${nodes} nodes generated, map generated: ${map}`)
}

makeboard(10, 2)

这是我的震中 class

// adds an epicenter for an earthquake which can be placed on the board
   class Epicenter {
    constructor(lat, long, magnitude, width) {
      this.lat = lat;
      this.long = long;
      this.magnitude = magnitude;
      this.width = width;
    }

    shiftMagnitude(){
      this.magnitude = Math.floor(Math.random(10)+this.magnitude);
      console.log('Magnitude of epicenter has changed')
    }
  }

我的package.json

也供参考

{
  "name": "edge_testing_lab",
  "version": "1.0.0",
  "description": "testing lab",
  "main": "generateMap.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "person",
  "license": "ISC"
}

Answer 1

您应该 export 您的 class 如下所示：


// adds an epicenter for an earthquake which can be placed on the board
class Epicenter {
    constructor(lat, long, magnitude, width) {
      this.lat = lat;
      this.long = long;
      this.magnitude = magnitude;
      this.width = width;
    }

    shiftMagnitude(){
      this.magnitude = Math.floor(Math.random(10)+this.magnitude);
      console.log('Magnitude of epicenter has changed')
    }
  }
module.exports = Epicenter;

配置 "type": "module" 用于 ES modules 对 nodejs 软件包的支持。因此其他包可以处理使用带有最后 Node.js 版本的本机 import 的包。

class 的构造函数在模块中 require 之后未定义

constructor for class is undefined after require in module

node.js

import

export

construct