Uncaught ReferenceError: __importDefault is not defined

问题

I am new to angular. I encounter this error in my index.component.ts file.

Uncaught ReferenceError: __importDefault is not defined

Error screenshot attached

回答1:

The following error is due to a bad version of typescript. You have to downgrade it.

Uncaught ReferenceError: __importDefault is not defined

Go to your package.json file and downgrade it to 3.5.3:

"devDependencies": {
    // ...
    "typescript": "3.5.3"
  }

回答2:

I got this problem when upgrading from 8 to 9, thought it was a bug and even started reporting it in https://github.com/angular/angular/issues/35208, but I'm not sure it is really a bug. It might help someone having this error, though, so I'm posting here.

Short answer:

For some reason Because I updated Angular CLI without running the migrations (due to some very particular constraints I had), my package.json was like this (those dependencies were left behind):

  "devDependencies": {
    "@angular-devkit/build-angular": "^0.803.20",
    "@angular-devkit/build-ng-packagr": "~0.803.20",
    ....

After changing it to the versions below, the problem is gone The problem wouldn't happen if they were as follows:

  "devDependencies": {
    "@angular-devkit/build-angular": "~0.900.1",
    "@angular-devkit/build-ng-packagr": "~0.900.1",
    ....

Keep in mind that I show the wrong/right package versions here so it's easy to identify the symptoms, but I do not recommend you updating them manually, please run the CLI migration (as explained in the ticket) and they will be updated correctly.

回答3:

I had the same problem when I update my project from angular 7 to 8. after running ng serve I git:

ERROR in The Angular Compiler requires TypeScript >=3.4.0 and <3.6.0 but 3.6.2 was found instead.

After that:

"Uncaught ReferenceError: __importDefault is not defined.

I run npm install typescript@~3.4.0 and my problem was solve.

回答4:

I got this problem when upgrading from 6 to 8, this is due to typescript, and adding below code to index.html will resolve issue

<script> var __importDefault = (this && this.__importDefault) || function (mod) { return (mod && mod.__esModule) ? mod : { "default": mod }; }</script>

来源：https://stackoverflow.com/questions/57662571/uncaught-referenceerror-importdefault-is-not-defined