angular - o.Subject 不是构造函数 - Angular 10

Question

Ng serve和ng build --prod命令工作正常，但是当我在 serve 上部署应用程序时，会出现以下错误：-

TypeError: o.Subject is not a constructor
at new e (vendor-esnext.js:1)
at Object.useFactory (vendor-esnext.js:1)
at Object.i [as factory] (vendor-esnext.js:1)
at Xo.hydrate (vendor-esnext.js:1)
at Xo.get (vendor-esnext.js:1)
at Jf.get (vendor-esnext.js:1)
at Object.get (vendor-esnext.js:1)
at Gn (vendor-esnext.js:1)
at Module.Sl (vendor-esnext.js:1)
at Mn.e.ɵfac [as factory] (vendor-esnext.js:1)

---

tsconfig.base.json

{"compilerOptions": {
"baseUrl": "",
"allowSyntheticDefaultImports": true,
"declaration": false,
"downlevelIteration": true,
"emitDecoratorMetadata": true,
"experimentalDecorators": true,
"lib": [
  "dom",
  "es2017"
],
"module": "esnext",
"moduleResolution": "node",
"sourceMap": true,
"target": "ESNext",
"paths": {
  "@angular/*": [
    "node_modules/@angular/*"
  ]
}},"include": [
"src/**/*.ts",
"node_modules/ng4-fittext/*.d.ts"],"exclude": [],"compileOnSave": false,}

Answer 1

import如果您将主题声明替换如下，该问题将在 Angular 10 及更高版本中得到解决。

代替：

import { Subject } from "rxjs/Subject";

和：

import { Subject } from "rxjs";

Answer 2

如果您来这里解决 angular-2-dropdown-multiselect 的问题，只需更新到最新版本。（实际上是 1.9.0）。