WebStorm 2016.3 error: Experimental support for decorators is a feature that is subject to change in a future release

WS2016.3 applies config settings to a file only if the file is included in 'files' or 'include' tsconfig.json section. [More info about tsconfig.json]

So the config must include all project files (or if you have several parts of the app you can have several tsconfig.json files). Otherwise typescript service uses default typescript options for the file.

Preferred solution

Your tsconfig.json should be:

{
  "version": "1.5.0",
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "noImplicitAny": false,
    "removeComments": true,
    "noLib": false,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true, 
    "sourceMap": true,
    "listFiles": true,
    "isolatedModules": false,
    "moduleResolution": "node",
    "suppressImplicitAnyIndexErrors": true
  },
  "include": [
    "typings/thera/thera.d.ts",
    "typings/browser.d.ts",
    "typings/main.d.ts",
    "typings/meteor.d.ts",
    "typings/meteor_server.d.ts",
    "your_app_directory/**/*" 
  ],
  "exclude": [ "node_modules" ],
  "compileOnSave":false //not required but is suggested for meteor projects
}

Another solution

You can specify default options in the TypeScript settings (track changes option should be unchecked if you don't want auto compilation):

Note: If you don't like the new behaviour you can disable the typescript service integration in "File | Settings | Languages & Frameworks | TypeScript" -> "Use TypeScript service".

Works in WebStorm 2020.1.2 as well. Thanks.

1. Open File -> Settings -> Languages & Frameworks -> Typescript
2. In Options input add --experimentalDecorators --moduleResolution mode

Click the apply button at the bottom right