Typescript: TS2403: Subsequent variable declarations must have the same type. After NPM install

[AcousticGuitar]

TypeScript Version: 2.2.2

Code
This is my TSCConfig file content

{
    "compilerOptions": {
        "module": "amd",
        "moduleResolution": "node",
        "target": "es5",
        "noImplicitAny": false,
        "jsx": "react",
        "sourceMap": false,
        "baseUrl": ".",
        "paths": {
            "OfficeFabric/*": [
                "node_modules/office-ui-fabric-react/lib-amd/*"
            ]
        }
    } 
}

Expected behavior:
After running npm install @ types/node --save
The project should compile ok.
Actual behavior:
The error message TS2403 is indicated.
Uninstalling the node types fixes the problem.

Could this be a clash between : module:"amd" and moduleresolution: "node"

Current Node version is 7.0.3
The installed types was for version + @types/[email protected]

[andy-ms]

We would need to know the variable that is causing you this problem, and the places where it is defined.

[AcousticGuitar]

The error is calling out the index.d.ts Type definition file here.
This file is found here: node_modules\@types\node\index.d.ts

[andy-ms]

There must be another definition of require somewhere.

[AcousticGuitar]

I'm using React, when the TSX files are compiled; they produce this JS equivalent as first line of JS file.

define(["require", "exports", "react", "OfficeFabric/components/DetailsList/DetailsList"], function (require, exports, React, DetailsList_1)

Could that be it?

[andy-ms]

Try using find-all-references on declare var require. It should show you another declare var require with a different type.

[AcousticGuitar]

Project is not in Visual Studio, rather VS Code, find all require shows no other vars being declared but I'll look again.

[AcousticGuitar]

declare var noderequire: Require; from vss.d.ts (The VSTS extension SDK)
declare var require : noderequire from index.d.ts (for Node)

TS2403: Subsequent variable declarations must have the same type. Variable 'require' must be of type 'Require', but here has type 'NodeRequire'.

Maybe it's these two that are conflicting?

[andy-ms]

Not if they have different names (noderequire vs require). Find-all-references should work in vscode -- right click on require.

[AcousticGuitar]

Ok maybe I found it..... I renamed the var require to nrequire and then searched project for all nrequires. This is what it found:

Looks like there is a variable conflict between Node and Require.

[andy-ms]

It doesn't make sense to use both of those types at once, since require.js doesn't run on node. Use the --types compiler option to choose just the types you need.

[AcousticGuitar]

andy,
Thanks so much for your help I think I understand this now!

[mhegazy]

Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.

[CJ-Johnson]

I had the same error and solved it by manually adding tslint and tslint-react to the package.json. It was installed globally before and so switching node versions with nvm was causing issues.

[jstaro]

So what is the proper way to solve this? I see the mention of --types, but...

I started getting this error after upgrading to the latest version of jest, whose typings have the NodeRequire declaration, and my app also has a global declaration of require as follows:

globals.d.ts

declare var require: {
    <T>(path: string): T | any;
    (paths: string[], callback: (...modules: any[]) => void): void | any;
    ensure: (paths: string[], callback: (require: <T>(path: string) => T) => void, chunkName?: string) => void | any;
    context: any;
};

tsconfig.json

{
  "buildOnSave": false,
  "compileOnSave": false,
  "compilerOptions": {
    "module": "commonjs",
    "target": "es5",
    "lib": [
      "dom",
      "es2015"
    ],
    "allowJs": true,
    "sourceMap": true,
    "jsx": "preserve",
    "downlevelIteration": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "strict": true,
    "strictNullChecks": false,
    "removeComments": true
  },
  "exclude": [
    "node_modules",
    "build",
    "dist",
    "__mocks__",
    "coverage",
    "*.config.js",
    "*.babel.js",
    "specs"
  ],
  "types": [
    "wwwroot/app/globals.d.ts"
  ]
}

As I understand it, if types is defined as an array, it should not automatically use globals from node_modules when typechecking (from the Handbook: "If types is specified, only packages listed will be included."), so why do I get this error when I run tsc (and build via webpack)?

[jstaro]

For now, I did this, which seems to work, but feels like a hack:

interface AppRequire {
    <T>(path: string): T | any;
    (paths: string[], callback: (...modules: any[]) => void): void | any;
    ensure: (paths: string[], callback: (require: <T>(path: string) => T) => void, chunkName?: string) => void | any;
    context: any;
}

interface NodeRequire extends AppRequire {}

[andy-ms]

@jstaro It looks like Jest defines an interface NodeRequire but doesn't actually declare the require variable -- I think you could just ignore it then?

[Thavaprakash]

Hi All,

I'm getting similar error in should npm. Please help me to fix it.

node_modules/should/should.d.ts(237,5): error TS2403: Subsequent variable declarations must have the same type. Variable 'should' must be of type 'Assertion', but here has type 'Assertion'.

node version: v8.9.1
npm version: 5.5.1
"should": "^13.2.1"

[andy-ms]

@Thavaprakash You probably have 2 such errors -- one in this location and one in another location. For example, you might accidentally have 2 versions of "should" installed that are incompatible.

[Thavaprakash]

@andy-ms Thanks for your prompt reply, I don't have 2 versions of "should". I grepped, i found only one place.

# grep 'should: should.Assertion' * -inr
node_modules/should/should.d.ts:237: should: should.Assertion;

[andy-ms]

@Thavaprakash OK, could you find-all-references on should to look for the other declaration?

[Thavaprakash]

should references in many places, we can't dig into that. I tried this, it works but why this global variable

[andy-ms]

You could also go-to-definition on any of the references and you will probably see two definitions.

[Thavaprakash]

Thanks @andy-ms , Issue is fixed