Angular CLI - Typescript throws: Cannot read property 'length' of undefined

问题

I run in angular 4 project with ng serve and i get error

Cannot read property 'length' of undefined

but I don't have any property length in my project..

the full error

    Your global Angular CLI version (1.2.1) is greater than your local
version (1.1.3). The local Angular CLI version is used.

To disable this warning use "ng set --global warnings.versionMismatch=false".
Cannot read property 'length' of undefined
TypeError: Cannot read property 'length' of undefined
    at createSourceFile (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:15457:109)
    at parseSourceFileWorker (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:15389:26)
    at Object.parseSourceFile (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:15338:26)
    at Object.createSourceFile (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:15192:29)
    at VirtualFileStats.getSourceFile (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\@ngtools\webpack\src\compiler_host.js:66:35)
    at WebpackCompilerHost.getSourceFile (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\@ngtools\webpack\src\compiler_host.js:213:38)
    at findSourceFile (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:67909:29)
    at processImportedModules (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:68056:25)
    at findSourceFile (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:67937:17)
    at processImportedModules (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:68056:25)
    at findSourceFile (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:67937:17)
    at processSourceFile (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:67840:27)
    at processRootFile (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:67728:13)
    at E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:67018:60
    at Object.forEach (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:1449:30)
    at Object.createProgram (E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master\node_modules\typescript\lib\typescript.js:67018:16)
PS E:\פרוייקטים\פרוייקטים קיץ\Angular 4\Youtube Channel Angular Firebase\full project of the instructor github\angular-firestarter-master>

package.json

{
  "name": "firestarter",
  "version": "0.0.0",
  "license": "MIT",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"
  },
  "private": true,
  "dependencies": {
    "@angular/animations": "^4.2.4",
    "@angular/common": "^4.2.4",
    "@angular/compiler": "^4.2.4",
    "@angular/core": "^4.2.4",
    "@angular/forms": "^4.2.4",
    "@angular/http": "^4.2.4",
    "@angular/platform-browser": "^4.2.4",
    "@angular/platform-browser-dynamic": "^4.2.4",
    "@angular/platform-server": "^4.2.4",
    "@angular/router": "^4.2.4",
    "@types/lodash": "^4.14.67",
    "angularfire2": "^4.0.0-rc.1",
    "core-js": "^2.4.1",
    "firebase": "^4.1.3",
    "lodash": "^4.17.4",
    "rxjs": "^5.4.1",
    "zone.js": "^0.8.12"
  },
  "devDependencies": {
    "@angular/cli": "^1.1.3",
    "@angular/compiler-cli": "^4.2.4",
    "@types/jasmine": "2.5.53",
    "@types/node": "~8.0.4",
    "codelyzer": "~3.1.1",
    "jasmine-core": "~2.6.4",
    "jasmine-spec-reporter": "~4.1.1",
    "karma": "~1.7.0",
    "karma-chrome-launcher": "~2.2.0",
    "karma-cli": "~1.0.1",
    "karma-coverage-istanbul-reporter": "^1.3.0",
    "karma-jasmine": "~1.1.0",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~5.1.2",
    "ts-node": "~3.1.0",
    "tslint": "~5.4.3",
    "typescript": "=2.3.4"
  }
}

回答1:

You might be missing one or more files that typescript is trying to process. To find out which file you are missing just add

console.log(fileName);

at the starting of the createSourceFile function at node_modules/typescript/lib/typescript.js file.

回答2:

Most likely you have changed around your modules in a way that needs the CLI to be restarted.

I had the same error running ng serve after removing a component from a module. By restarting that process and re running ng serve the error went away.

回答3:

My problem was that, for some reason, my envioroment.ts file was missing. So check important files.

回答4:

My error was caused by c&p error when creating a small component. I forgot to change path to component's template and styles.

回答5:

I solved this problem (error during refactoring test). All is good for angular v4.3.* and v4.4*

Change @angular/cli version 1.7.3 to 1.4.10 in package.json (latest for angular4)
rm -rf node_modules
npm install --no-optional

回答6:

In my case I did the following and it solved the issue:

Create environments folder (if not exist) in src of the Project C:\Users\abcd\Desktop\MyApp\src
Put the two files environment.ts and environment.prod.ts in environments folder.

来源：https://stackoverflow.com/questions/45219750/angular-cli-typescript-throws-cannot-read-property-length-of-undefined

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angular

angular-cli