Uncaught ReferenceError: __importDefault is not defined

Question

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

Uncaught ReferenceError: __importDefault is not defined

Error screenshot attached

Answer 1

I got this problem when i was upgrading from angular 6 to angular 8, this is due to typescript, since my TypeScript version cannot be downgraded, I have overridden this method. adding below code to index.html will resolve issue

GitHub Issue

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

Answer 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.

Answer 3

This fixed it for me.

Added these lines to polyfills.ts:

const w: any = window
// Fix "missing __importDefault", as per https://github.com/angular/angular/issues/32215#issuecomment-543459862
w.__importDefault = (w && w.__importDefault) || function (mod) { return (mod && mod.__esModule) ? mod : { "default": mod }; }