Typescript: In JS, `object` is treated as 'any'

[andy-ms]

TypeScript Version: 3.0.0-dev.20180711

Code

/** @typedef {object} T */
/** @type {T} */
const x = 0;

Expected behavior:

Error at x: 0 is not an object.

Actual behavior:

No error.

[sandersn]

I think this is a result of Object/object being treated as any. For example, /** @typedef {{}} T */ produces an error.

[sandersn]

In getTypeFromTypeNode, we have:

case SyntaxKind.ObjectKeyword:
    return node.flags & NodeFlags.JavaScriptFile ? anyType : nonPrimitiveType

This was originally added in #17082. We could revisit this decision, but case-insensitive primitives and Object as any are good decisions in my opinion.

[andy-ms]

Solution may be to add a new type which is definitely the same as ts's object regardless of what kind of file it appears in.

[sandersn]

Maybe type NonPrimitive = object in lib.d.ts?

[thorn0]

can be closed as fixed by https://github.com/microsoft/TypeScript/pull/35661 ?

[sandersn]

Maybe. #35661 only applies when noImplicitAny: true though.

[ExE-Boss]

I’d like if there was a way to use the object type in JSDoc without needing to enable noImplicitAny.

[sandersn]

@ExE-Boss you can use the type NonPrimitive = object in one of your own d.ts files. Unfortunately, lots of existing JS code uses object to mean any or unknown, even projects like webpack that compile regularly with typescript.