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typescripttypesanytsconfig
RyanNHG
RyanNHG

Reputation: 1069

Typescript: Strict Checks Against "Any"

My Typescript configuration is allowing the following code to compile:

const thing : any = 123
const name : string = thing

Clearly, name is not actually a string, but the fact that I declare it as any makes my typechecker ignore it.

How can I configure my tsconfig.json to give me an error until I provide the correct types for my object?

My current configuration:

{
    "compilerOptions": {
        "module": "commonjs",
        "target": "es6",
        "noEmitOnError": true,
        "noImplicitAny": true,
        "noImplicitReturns": true,
        "noUnusedLocals": true,
        "noUnusedParameters": true,
        "strictNullChecks": true,
        "moduleResolution": "node",
        "sourceMap": true,
        "outDir": "dist",
        "baseUrl": ".",
        "paths": {
            "*": [
                "node_modules/*",
                "src/types/*"
            ]
        }
    },
    "include": [
        "src/**/*.ts"

    ]
}

Upvotes: 3

Views: 2317

Answers (2)

JojOatXGME
JojOatXGME

Reputation: 3296

The type any disables the type checker by design. As of TypeScript 3.0, there is another type called unknown which is basically a strict version of any.

const thing: unknown = 123;
const name: string = thing; // <- error TS2322: Type 'unknown' is not assignable to type 'string'.

You can find more about it in the release notes of TypeScript 3.0. For now – about two years after release –, the type is not yet listed as one of the basic types on the website. However, there is a beta for a new version of the website which also lists unknown.

Upvotes: 1

basarat
basarat

Reputation: 276269

but the fact that I declare it as any makes my typechecker ignore it.

This is by design. By saying its any you are explicitly asking the type checker to ignore it, and that is what it does 🌹

Upvotes: 3

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