Angular SSR - 未定义 ReferenceError

Question

错误

ERROR Error: Uncaught (in promise): ReferenceError: fetch is not defined
ReferenceError: fetch is not defined
    at toDataURL (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:349225:28)
    at D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:351030:88
    at Array.forEach (<anonymous>)
    at GametypeService.get gameTypes [as gameTypes] (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:351028:28)
    at GameTypesResolver.resolve (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:349524:37)
    at getResolver (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:148646:59)
    at MergeMapSubscriber.project (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:148632:146)
    at MergeMapSubscriber._tryNext (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:321242:27)
    at MergeMapSubscriber._next (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:321232:18)
    at MergeMapSubscriber.next (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:316467:18)
    at resolvePromise (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:332672:39)
    at resolvePromise (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:332624:21)
    at D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:332734:21
    at ZoneDelegate../node_modules/zone.js/dist/zone-node.js.ZoneDelegate.invokeTask (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:332261:35)
    at Object.onInvokeTask (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:85361:33)
    at ZoneDelegate../node_modules/zone.js/dist/zone-node.js.ZoneDelegate.invokeTask (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:332260:40)
    at Zone../node_modules/zone.js/dist/zone-node.js.Zone.runTask (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:332028:51)
    at drainMicroTaskQueue (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:332441:39)
    at ./node_modules/zone.js/dist/zone-node.js.ZoneTask.invokeTask (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:332347:25)
    at Server.ZoneTask.invoke (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:332332:52) {
  rejection: ReferenceError: fetch is not defined
      at toDataURL (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:349225:28)
      at D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:351030:88
      at Array.forEach (<anonymous>)
      at GametypeService.get gameTypes [as gameTypes] (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:351028:28)
      at GameTypesResolver.resolve (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:349524:37)
      at getResolver (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:148646:59)
      at MergeMapSubscriber.project (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:148632:146)
      at MergeMapSubscriber._tryNext (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:321242:27)
      at MergeMapSubscriber._next (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:321232:18)
      at MergeMapSubscriber.next (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:316467:18),
  promise: ZoneAwarePromise [Promise] {
    __zone_symbol__state: 0,
    __zone_symbol__value: ReferenceError: fetch is not defined
        at toDataURL (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:349225:28)
        at D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:351030:88
        at Array.forEach (<anonymous>)
        at GametypeService.get gameTypes [as gameTypes] (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:351028:28)
        at GameTypesResolver.resolve (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:349524:37)
        at getResolver (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:148646:59)
        at MergeMapSubscriber.project (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:148632:146)
        at MergeMapSubscriber._tryNext (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:321242:27)
        at MergeMapSubscriber._next (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:321232:18)
        at MergeMapSubscriber.next (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:316467:18)
  },
  zone: Zone {
    _parent: Zone {
      _parent: null,
      _name: '<root>',
      _properties: {},
      _zoneDelegate: [ZoneDelegate]
    },
    _name: 'angular',
    _properties: { isAngularZone: true, maybeDelayChangeDetection: false },
    _zoneDelegate: ZoneDelegate {
      _taskCounts: [Object],
      zone: [Circular],
      _parentDelegate: [ZoneDelegate],
      _forkZS: null,
      _forkDlgt: null,
      _forkCurrZone: null,
      _interceptZS: null,
      _interceptDlgt: null,
      _interceptCurrZone: null,
      _invokeZS: [Object],
      _invokeDlgt: [ZoneDelegate],
      _invokeCurrZone: [Circular],
      _handleErrorZS: [Object],
      _handleErrorDlgt: [ZoneDelegate],
      _handleErrorCurrZone: [Circular],
      _scheduleTaskZS: [Object],
      _scheduleTaskDlgt: [ZoneDelegate],
      _scheduleTaskCurrZone: [Circular],
      _invokeTaskZS: [Object],
      _invokeTaskDlgt: [ZoneDelegate],
      _invokeTaskCurrZone: [Circular],
      _cancelTaskZS: [Object],
      _cancelTaskDlgt: [ZoneDelegate],
      _cancelTaskCurrZone: [Circular],
      _hasTaskZS: [Object],
      _hasTaskDlgt: [ZoneDelegate],
      _hasTaskDlgtOwner: [Circular],
      _hasTaskCurrZone: [Circular]
    }
  },
  task: ZoneTask {
    _zone: Zone {
      _parent: [Zone],
      _name: 'angular',
      _properties: [Object],
      _zoneDelegate: [ZoneDelegate]
    },
    runCount: 0,
    _zoneDelegates: null,
    _state: 'notScheduled',
    type: 'microTask',
    source: 'Promise.then',
    data: ZoneAwarePromise [Promise] {
      __zone_symbol__state: 0,
      __zone_symbol__value: ReferenceError: fetch is not defined
          at toDataURL (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:349225:28)
          at D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:351030:88
          at Array.forEach (<anonymous>)
          at GametypeService.get gameTypes [as gameTypes] (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:351028:28)
          at GameTypesResolver.resolve (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:349524:37)
          at getResolver (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:148646:59)
          at MergeMapSubscriber.project (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:148632:146)
          at MergeMapSubscriber._tryNext (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:321242:27)
          at MergeMapSubscriber._next (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:321232:18)
          at MergeMapSubscriber.next (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:316467:18)
    },
    scheduleFn: undefined,
    cancelFn: undefined,
    callback: [Function],
    invoke: [Function]
  }
}

ERROR NetworkError
    at XMLHttpRequest.send (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:329773:19)
    at Observable._subscribe (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:28155:17)
    at Observable._trySubscribe (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:315923:25)
    at Observable.subscribe (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:315909:22)
    at scheduleTask (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:144497:32)
    at Observable._subscribe (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:144535:13)
    at Observable._trySubscribe (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:315923:25)
    at Observable.subscribe (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:315909:22)
    at innerSubscribe (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:316912:23)
    at MergeMapSubscriber._innerSub (D:\Github\CountYourDrinks\dist\Worth-a-shot\server\main.js:321255:105)

我理解的问题

据我所知，服务器端功能并不总是支持前端库，在这种情况下，服务器不支持 fetch API，所以我应该用具有相同功能的东西替换它。

我可以删除 fetch 的所有功能，并且不会对我的代码产生太大影响。但是，这似乎是一个糟糕的解决方案，我相当确定我会在使用其他库或客户端 API（例如 window 和 localStorage）时遇到此错误。

我的尝试

我已经阅读了所有我能找到的错误报告，但这并没有太大帮助。

我尝试将以下代码块添加到我的 server.ts 或 main.server.ts 文件中：

global['fetch'] = null;

或

export const fetch = require("node-fetch");`

或

const fetch = require("node-fetch");`

或

var fetch = require("node-fetch");`

或

import fetch from 'node-fetch';

但没有任何帮助。

我想我有些了解这个问题，但我不明白如何解决它。

额外，我不确定这是否有帮助

main.server.ts

import { enableProdMode } from '@angular/core';

import { environment } from './environments/environment';

if (environment.production) {
  enableProdMode();
}

export { AppServerModule } from './app/app.server.module';
export { renderModule, renderModuleFactory } from '@angular/platform-server';

server.ts

import 'zone.js/dist/zone-node';

import { ngExpressEngine } from '@nguniversal/express-engine';
import * as express from 'express';
import { join } from 'path';

import { AppServerModule } from './src/main.server';
import { APP_BASE_HREF } from '@angular/common';
import { existsSync } from 'fs';

// The Express app is exported so that it can be used by serverless Functions.
export function app(): express.Express {
  const server = express();
  const distFolder = join(process.cwd(), 'dist/Worth-a-shot/browser');
  const indexHtml = existsSync(join(distFolder, 'index.original.html')) ? 'index.original.html' : 'index';

  // Our Universal express-engine (found @ https://github.com/angular/universal/tree/master/modules/express-engine)
  server.engine('html', ngExpressEngine({
    bootstrap: AppServerModule,
  }));

  server.set('view engine', 'html');
  server.set('views', distFolder);

  // Example Express Rest API endpoints
  // server.get('/api/**', (req, res) => { });
  // Serve static files from /browser
  server.get('*.*', express.static(distFolder, {
    maxAge: '1y'
  }));

  // All regular routes use the Universal engine
  server.get('*', (req, res) => {
    res.render(indexHtml, { req, providers: [{ provide: APP_BASE_HREF, useValue: req.baseUrl }] });
  });

  return server;
}

function run(): void {
  const port = process.env.PORT || 4000;

  // Start up the Node server
  const server = app();
  server.listen(port, () => {
    console.log(`Node Express server listening on http://localhost:${port}`);
  });
}

// Webpack will replace 'require' with '__webpack_require__'
// '__non_webpack_require__' is a proxy to Node 'require'
// The below code is to ensure that the server is run only when not requiring the bundle.
declare const __non_webpack_require__: NodeRequire;
const mainModule = __non_webpack_require__.main;
const moduleFilename = mainModule && mainModule.filename || '';
if (moduleFilename === __filename || moduleFilename.includes('iisnode')) {
  run();
}

export * from './src/main.server';