Support for deno.config.ts or Extending Configuration in deno.json

[mikoloism]

I propose an enhancement to the Deno configuration system that introduces two options for configuration management:

1. Support for TypeScript Configuration Files: Allow users to define their Deno configuration in a TypeScript file (deno.config.ts), enabling the use of module imports for shared configurations.

2. Extending JSON Configuration Files: Enable deno.json to reference and extend configurations from other JSON files, reducing redundancy and improving maintainability.

Motivation:

1. Avoiding Redundancy: Currently, when configuring properties like fmt, users must rewrite all properties in deno.json. This can lead to duplication and increased maintenance overhead. By allowing configuration files to extend other files, users can manage shared settings more efficiently.

2. Modular Configuration: Using a TypeScript configuration file allows developers to import shared configurations as modules. This promotes code reuse and makes it easier to manage complex configurations across multiple projects.

3. Improved Developer Experience: Both options would enhance the developer experience by simplifying configuration management and reducing the likelihood of errors due to duplication.

Proposed Implementation:

TypeScript Configuration:

// deno.config.ts
import fmtConfig from "./configs/deno.fmt.ts";

const config = {
  fmt: fmtConfig,
};

export default config;

Extending JSON Configuration:

// deno.json(c)
{
  "fmt": "./configs/deno.fmt.json"
}

// ./configs/deno.fmt.json
{
  "printWidth": 80
}

[dsherret]

Support for TypeScript Configuration Files: Allow users to define their Deno configuration in a TypeScript file (deno.config.ts), enabling the use of module imports for shared configurations.

This was discussed when initially adding a configuration file to Deno and it was rejected because it will greatly negatively impact startup performance.

Extending JSON Configuration Files: Enable deno.json to reference and extend configurations from other JSON files, reducing redundancy and improving maintainability.

Follow #18132 for extending configs.

(Marked this as duplciate of #18132, but then declined for deno.config.ts since this is two issues in one)