hsh

Lightweight log-level mapper — because sometimes you just need a little hsh.

This package provides a tiny function that maps string input to log levels. It supports:

• A single default log level (e.g., debug, info, ...)
• A comma-separated map like serviceA=debug,serviceB=error,default=warn

It returns a small helper with a get(key) method so you can ask for the log level of a component/service and fall back to a default.

Installation

npm install hsh

Usage

Use a single level for all components:

import hsh from "hsh";

const levels = hsh("debug");
levels.get("anything"); // "debug"

Or provide a map string to configure per-key levels with a default:

import hsh from "hsh";

const levels = hsh("serviceA=debug,serviceB=error,default=warn");
levels.get("serviceA"); // "debug"
levels.get("serviceB"); // "error"
levels.get("other"); // "warn" (default)

Accepted log levels are exactly: trace, debug, info, warn, error, fatal, silent.

Invalid levels are coerced to warn by the validator.

Notes:

• Keys in the map must be alphanumeric (as defined by the regex in source).
• Level strings are case-insensitive; they will be lowercased during parsing.

API

• Default export: hsh(input: string): { get(key: string): LogLevel }
  • input can be a single level or a map string as shown above.
  • get(key) returns the configured level for key or the default level. If no default is provided, it falls back to warn.

Environment variables

The library itself does not read environment variables. A common pattern is to pass a string from an env var into hsh().

You can use the environment variable HSH and wire it in your application like this:

import hsh from "hsh";

// Read from process.env.HSH with a sensible fallback
const levels = hsh(process.env.HSH ?? "warn");

// Later in your code
levels.get("my-service"); // resolves based on HSH or falls back to "warn"

Examples:

• Single level for everything:
  • HSH=debug node app.js
• Map with per-key levels and a default:
  • HSH="serviceA=debug,serviceB=error,default=info" node app.js

Notes:

• If HSH is unset or empty, choose a default (e.g., "warn") as shown above.
• Invalid values are coerced to "warn" by the validator, and missing default in maps also falls back to "warn".
• Keys must be alphanumeric and levels are case-insensitive.

License

MIT