Add .getObjectType() to the TypeChecker

[mrazauskas]

🔍 Search Terms

"getNonPrimitiveType", "getObjectType", "TypeChecker"

✅ Viability Checklist

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
• This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

⭐ Suggestion

I would like to propose adding .getObjectType() method to the TypeChecker. Similar to methods like .getAnyType() or .getUndefinedType(), the returned type of .getObjectType() would be the Type of the object type.

Alternative name: .getNonPrimitiveType(). Same as the variable is named:

var nonPrimitiveType = createIntrinsicType(TypeFlags.NonPrimitive, "object");

📃 Motivating Example

If I see it right object is the only intrinsic / built-in type that does not have a .get method. Might be this is intentional and also might be object isn’t considered intrinsic.

The motivation is to fill in a gap. If there is one.

Somewhat similar to: #59256

💻 Use Cases

1. What do you want to use this for?

The project I am working on is using TypeScript programatically. The object type is used to validate user input. A user provides a type and the logic checks if that type is assignable to the object type. If not, a friendly message is printed that an object type was expected.

2. What shortcomings exist with current approaches?

As a workaround, I create a fake type. Obviously this cannot work with TypeScript 7 anymore.

3. What workarounds are you using in the meantime?

const nonPrimitiveType = { flags: this.#compiler.TypeFlags.NonPrimitive } as ts.Type; // the intrinsic 'object' type

if (!typeChecker.isTypeAssignableTo(sourceType, nonPrimitiveType)) {
  // skipped
};

[RyanCavanaugh]

Yeah, it seems like this one is missing relative to the rest. Accepting PRs

[mrazauskas]

Thanks for response. I will try to put together a PR. Which name do you prefer .getObjectType() or better .getNonPrimitiveType().

As I mentioned, the internal variable as well as type flag are named NonPrimitive (probably because TypeFlags.Object was taken already):

var nonPrimitiveType = createIntrinsicType(TypeFlags.NonPrimitive, "object");

[RyanCavanaugh]

NonPrimitive seems correct