如何将变量从一个javascript文件传递到另一个javascript文件？

我正试图修改github repo:中的代码，以便在Google app engine上使用，但我在将变量从/app.js传递到/books/crud.js时遇到了一个问题。我已经将google身份验证添加到app.js中，因此可以访问该文件中用户的电子邮件地址，但当我尝试导出该变量并在crud.js中访问它时，它不起作用。我已尝试将变量添加到app.js底部的导出中，因此它的内容如下：

module.exports = { app, email };

然后使用以下语句将其导入crud.js中：

const appFile = require('../app');

并使用以下命令将变量从crud.js传递到.pug文件：

    router.get('/add', (req, res) => {
  res.render('books/form.pug', {
    book: {},
    action: 'Add',
    user: appFile.email
  });
});

但是，这不起作用，变量也无法通过。任何帮助都将不胜感激！ 以下是我正在使用的完整app.js文件：

'use strict';

// [START getting_started_auth_all]
const express = require('express');
const metadata = require('gcp-metadata');
const {OAuth2Client} = require('google-auth-library');

const app = express();
const oAuth2Client = new OAuth2Client();

var user = "";

// Cache externally fetched information for future invocations
let aud;
// [START getting_started_auth_metadata]
async function audience() {
  if (!aud && (await metadata.isAvailable())) {
    let project_number = await metadata.project('numeric-project-id');
    let project_id = await metadata.project('project-id');

    aud = '/projects/' + project_number + '/apps/' + project_id;
  }

  return aud;
}
// [END getting_started_auth_metadata]

// [START getting_started_auth_audience]
async function validateAssertion(assertion) {
  if (!assertion) {
    return {};
  }

  // Check that the assertion's audience matches ours
  const aud = await audience();

  // Fetch the current certificates and verify the signature on the assertion
  // [START getting_started_auth_certs]
  const response = await oAuth2Client.getIapPublicKeys();
  // [END getting_started_auth_certs]
  const ticket = await oAuth2Client.verifySignedJwtWithCertsAsync(
    assertion,
    response.pubkeys,
    aud,
    ['https://cloud.google.com/iap']
  );
  const payload = ticket.getPayload();

  // Return the two relevant pieces of information
  return {
    email: payload.email,
    sub: payload.sub,
  };
}
// [END getting_started_auth_audience]
//[START getting_started_auth_front_controller]
let email = 'None';

app.get('/', async (req, res) => {
 const assertion = req.header('X-Goog-IAP-JWT-Assertion');

 try {
   const info = await validateAssertion(assertion);
   email = info.email;
 } catch (error) {
   console.log(error);
  }

  res.status(200).send(`Hello ${email}`).end();
});

// [END getting_started_auth_front_controller]
app.set('views', require('path').join(__dirname, 'views'));
app.set('view engine', 'pug');

// Books
app.use('/books', require('./books/crud'));
app.use('/api/books', require('./books/api'));

// Redirect root to /books
app.get('/', (req, res) => {
  res.redirect('/books');
});

app.get('/errors', () => {
  throw new Error('Test exception');
});

app.get('/logs', (req, res) => {
  console.log('Hey, you triggered a custom log entry. Good job!');
  res.sendStatus(200);
});

// Start the server
const port = process.env.PORT || 8080;
app.listen(port, () => {
  console.log(`App listening on port ${port}`);
});
module.exports = {
  app,
  email
  };

---

不能将变量从一个js文件传递到另一个js文件。 但是您可以通过包含HTML/PHP文件来使用来自不同js文件的变量

让我们来看两个js文件： one.js

x=10;

y=2;

和two.js

x=10;

y=2;

现在您有了一个index.html文件

<script type="text/javascript" src="1.js"></script>
<script type="text/javascript" src="2.js"></script>

<script>
    console.log(x+y);
</script>

控制台日志（x+y）；

控制台中的输出为12

---

JavaScript在环境而不是文件中执行。它没有在文件之间传递变量的概念。（阿法克）