[typescript] Experimental decorators warning in TypeScript compilation

I receive the warning...

Experimental support for decorators is a feature that is subject to change in a future release. Set the 'experimentalDecorators' option `to remove this warning.

... even though my compilerOptions in tsconfig.json have the following settings:

"emitDecoratorMetadata": true,
"experimentalDecorators": true,

What is weird is that some random classes that use decorators do not show that warning but the rest in the same project do.

What could cause such behavior in the TypeScript compiler?

Add following lines in tsconfig.json and restart VS Code.

{
    "compilerOptions": {
        "experimentalDecorators": true,
        "target": "es5",
        "allowJs": true
    }
}

You can also try with ng build. I've just rebuilt the app and now it's not complying.

1. Open VScode.
2. Press ctrl+comma
3. Follow the directions in the screen shot
   1. Search about experimentalDecorators
   2. Edit it

inside your project create file tsconfig.json , then add this lines

{
    "compilerOptions": {
        "experimentalDecorators": true,
        "allowJs": true
    }
}

So it turns out you can get around this by matching your module name to the file name. If you have the module name BankSpecialtyModule then the file name should be. bank-specialty.module.ts

Please follow the below step to remove this warning message.

Step 1: Go to setting in your IDE then find or search the experimentalDecorators.

Step 2: then click on checkbox and warning has been remove in your page.

Thank you Happy Coding ..........

I experienced this error when I created a new module and move my *.module.ts and *-routing.module.ts file to another folder. After I deleted the two files and created the module on the new folder it works perfectly. Environment Angular Version 9 and Angular CLI version 9.1.0

This error also occurs when you choose "src" folder for your workspace folder.

When the root folder, folder where the "src", "node_modules" are located is chosen, the error disappears

You might run into this issue if you open a TS file that exists outside of the project. For instance, I'm using lerna and had a file open from another package. Although that other package had it's own tsconfig with experimental decorators, VsCode doesn't honor it.

I faced the same issue while creating an Injectable Services in Angular 2. I have all the things at place in tsconfig.json .Still I was getting this error at ColorsImmutable line.

@Injectable()
export class ColorsImmutable {

And fix was to register the Service at module Level or Component Level using the providers array.

providers:[ColorsImmutable ],

in my case I solved this issue by setting "include": [ "src/**/*"] in my tsconfig.json file and restarting vscode. I've got this solution from a github issue: https://github.com/microsoft/TypeScript/issues/9335

If you using Deno JavaScript and TypeScript runtime and you enable experimentalDecorators:true in tsconfig.json or the VSCode ide settings. It will not work. According to Deno requirement, you need to provide tsconfig as a flag when running a Deno file. See Custom TypeScript Compiler Options

In my particular case I was running a Deno test and used.

$ deno test -c tsconfig.json

If it is a file, you have something like

 $ deno run -c tsconfig.json mod.ts

my tsconfig.json

{
  "compilerOptions": {
    "allowJs": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "module": "esnext"
  }
}

have to add typescript.tsdk to my .vscode/settings.json:

"typescript.tsdk": "node_modules/typescript/lib"

File -> Preferences -> Settings

In Visual Code Studio Go to File >> Preferences >> Settings, Search "decorator" in search field and Check the option as in image.

"javascript.implicitProjectConfig.experimentalDecorators": true

Will solve this problem.

For the sake of clarity and stupidity.

1) Open .vscode/settings.json.

2) Add "typescript.tsdk": "node_modules/typescript/lib" on it.

3) Save it.

4) Restart Visual Studio Code.

I had this error with following statement

Experimental support for decorators is a feature that is subject to change in a future release. Set the 'experimentalDecorators' option in your tsconfig or jsconfig to remove this warning.ts(1219)

It was there because my Component was not registered in AppModule or (app.module.ts) i simply gave the namespace like

import { abcComponent } from '../app/abc/abc.component';

and also registered it in declarations

Open entire project's folder instead of project-name/src

tsconfig.json is out of src folder

Please check you oppened in your VS Code the folder of the entire project and not only the src folder, because if you open only the src, then ts.config.json (located in the project folder) file will not be in scope, and VS will not recognize the experimental decorators parameters.

In my case this fixed all the problems related to this issue.

I've to add the following in the settings.json file of vscode to remove the warning.

"javascript.implicitProjectConfig.experimentalDecorators": true

VSCode -> Preferences -> Settings

UPDATE

As Clepsyd pointed out, this setting had been deprecated. You need to use now

"js/ts.implicitProjectConfig.experimentalDecorators":true

I added this option to tsconfig.json, "baseUrl": "front-end" Replace front-end with the name of your angular-cli project.

You can run with this code

 tsc .\src\index.ts --experimentalDecorators "true" --emitDecoratorMetadata "true"

If you are working in Visual studio. You can try this fix

1. Unload your project from visual studio
2. Go to your project home directory and Open "csproj" file.

3. Add TypeScriptExperimentalDecorators to this section as shown in image

   

   4. Reload the project in Visual studio.

see more details at this location.

In VSCode, Go to File => Preferences => Settings (or Control+comma) and it will open the User Settings file. Search "javascript.implicitProjectConfig.experimentalDecorators": true and then check the checkbox for experimentalDecorators to the file and it should fix it. It did for me.

I corrected the warning by removing "baseUrl": "", from the tsconfig.json file

Not to belabor the point but be sure to add the following to

• Workspace Settings not User Settings

under File >> Preferences >> Settings

"javascript.implicitProjectConfig.experimentalDecorators": true

this fixed the issue for me, and i tried quite a few suggestions i found here and other places.

Open settings.json file in the following location <project_folder>/.vscode/settings.json

or you can open the file from the menu as mentioned below

VSCode -> File -> Preferences -> Workspace Settings

Then add the following lines in settings.json file

{
    "typescript.tsdk": "node_modules/typescript/lib",
    "enable_typescript_language_service": false
}

That's all. You will see no warning/error regarding 'experimentalDecorators'

For me, this error "Experimental support for decorators is a feature that is subject to change in a future release. (etc)" only happened in VS Code in an Angular project and only when creating a new Service.

The solution above: "In Visual Code Studio Go to File >> Preferences >> Settings, Search "decorator" in search field and Checking the option JavaScript › Implicit Project Config: Experimental Decorators" solved the problem.

Also, stopping the ng serve in the terminal window and restarting it made the error disappear after recompile.

If you are using cli to compile *.ts files, you can set experimentalDecorators using the following command:

 tsc filename.ts --experimentalDecorators "true"

I had this problem recently under Visual Studio 2017 - turned out it was caused by a "feature" of VS - ignoring tsconfig.json when Build action is not set to Content.

So changing the Build action to Content and reloading the solution solved the problem.

This answer is intended for people who are using a Javascript project and not a Typescript one. Instead of a tsconfig.json file you may use a jsconfig.json file.

In the particular case of having the decorators warning you wan write inside the file:

{
    "compilerOptions": {
        "experimentalDecorators": true
    }
}

Fort the buggy behaviors asked, it's always better to specify the "include" in the config file, and restart the editor. E.g.

{
    "compilerOptions": {
        "target": "ES6",
        "experimentalDecorators": true
    },
    "include": [
        "app/**/*"
    ],
    "exclude": [
        "node_modules"
    ]
}

I get this warning displayed in vscode when creating a new Angular service with the

@Injectable({
  providedIn: 'root'
})

syntax (rather than providing the service in app.module.ts).

The warning persists until I reference the new service somewhere in the project. Once the service gets used the warning goes away. No typescript configuration or vscode settings changes necessary.