我正在创建一个 express.js 应用程序作为团队项目的一部分。我是 javascipt 新手，但这个任务最终落到了我身上。相关代码的目的是在单击按钮时使用一些用户定义的选项运行脚本，然后显示新页面并显示已在结果页面上生成的报告的链接。无论出于何种原因，这在应用程序启动后第一次不起作用，但如果您返回并重试，它会起作用。我原以为存在同步问题，可能存在，但似乎还存在数组变量未传递给 pug 的问题。几个星期以来，我一直在为此而头疼，并向我的教授寻求帮助（我们都不是计算机科学人员），但没有成功。请帮忙。

这是文件开头的应用程序变量、配置等：

// index.js

/**
 * Required External Modules
 */

const express = require("express");
const path = require("path");
const shell = require("shelljs");
const fs = require("fs");






/**
 * App Variables
 */

const app = express();
const port = process.env.PORT || "8000";
var ipAddresses;
var ipAddressesLink;








/**
 *  App Configuration
 */

app.set("views", path.join(__dirname, "views"));
app.set("view engine", "pug");
app.use(express.static(path.join(__dirname, "public")));
app.use(express.static(path.join(__dirname, "reports/html")));

//code to make html forms work
var bodyParser = require('body-parser');
app.use(bodyParser.urlencoded({ extended: false }));

这是让我一直失败的相关路线：

//Run script when post is rec'd from root and send to results page
app.post("/", (req, res) => {
    //take values and create complete command for Astrum script
    var commandString = 'bash /home/astrum/Main/Astrum.sh -s ' + req.body.speed + ' -h ' + req.body.host + ' -u ' + req.body.username + ' -p ' + req.body.password;
    var pathToReports = './reports/html';
  
    runScript(commandString);

    readFolder(pathToReports);
    
    renderPage();
    
    
    //Iterate thru filenames to create arrays for links and link labels
    function readFolder(pathValue) {

        fs.readdir(pathValue, (err, files) => {

            console.log(files)
                
            //variable & method for links to html records pages
            ipAddressesLink = files;

            console.log(ipAddressesLink);
            
            //variable and method to remove file extension for link labels in pug
            ipAddresses = files.map(removeExtension);

            
        });

    }

    //function to remove last five characters of each element
    function removeExtension(value) {

        return value.substring(0, value.length - 5);

    };

    //function to render the page
    function renderPage() {

        res.render("results", {ipAddressesLink, ipAddresses, title: 'Results'});

    }

    //function to execute command in shell
    function runScript(value) {

        shell.exec(value);

    }


    //show array on console for debugging
    console.log("type of record is: " + typeof ipAddressesLink);
    console.log(ipAddressesLink);
    console.log(ipAddresses);

    res.end();
});

这是引发错误的结果页面的 pug 模板，显然是一项正在进行的工作：

extends layout

block layout-content
  
  div.View
    
    div.Message
      
      div.Title
        
        h1 Astrum Network Analysis
      
        div.Body          
          
          div.multiple-group
          
            h3 Heading
            select(id='whitelist', name='whitelist' size='6' multiple)
              option(value="volvo") Volvo
              option(value="saab") Saab
              option(value="fiat") Fiat
              option(value="audi") Audi
              option(value="bmw") BMW


          div.form-group

            label(for='whitelistButton')
            input(type='submit' value='Whitelist Ports')


          h3 Hosts Found:  
            
            ul

              each val, index in ipAddressesLink

                li: a( href = val ) #{ipAddresses[index]}

这是我收到的错误消息：

TypeError: /home/astrum/Main/astrumApp/views/results.pug:36
    34|             ul
    35| 
  > 36|               each val, index in ipAddressesLink
    37| 
    38|                 li: a( href = val ) #{ipAddresses[index]}
    39| 

Cannot read property 'length' of undefined
    at eval (eval at wrap (/home/astrum/Main/astrumApp/node_modules/pug-runtime/wrap.js:6:10), <anonymous>:93:32)
    at eval (eval at wrap (/home/astrum/Main/astrumApp/node_modules/pug-runtime/wrap.js:6:10), <anonymous>:116:4)
    at template (eval at wrap (/home/astrum/Main/astrumApp/node_modules/pug-runtime/wrap.js:6:10), <anonymous>:119:7)
    at Object.exports.renderFile (/home/astrum/Main/astrumApp/node_modules/pug/lib/index.js:452:38)
    at Object.exports.renderFile (/home/astrum/Main/astrumApp/node_modules/pug/lib/index.js:442:21)
    at View.exports.__express [as engine] (/home/astrum/Main/astrumApp/node_modules/pug/lib/index.js:491:11)
    at View.render (/home/astrum/Main/astrumApp/node_modules/express/lib/view.js:135:8)
    at tryRender (/home/astrum/Main/astrumApp/node_modules/express/lib/application.js:640:10)
    at Function.render (/home/astrum/Main/astrumApp/node_modules/express/lib/application.js:592:3)
    at ServerResponse.render (/home/astrum/Main/astrumApp/node_modules/express/lib/response.js:1012:7)