emit-deprecation

A type-safe helper for emitting deprecation warnings in Node projects.

Installation

npm install emit-deprecation

Usage

Usually, you'll want to create your deprecation emitter in its own file, then import it from other files to use it, like so:

// deprecations.js
import createDeprecationEmitter from 'emit-deprecation';

const emitDeprecation = createDeprecationEmitter('mathfuncs', {
	ADD_THREE: 'add(a, b, c) is deprecated. Use add(a, add(b, c)) instead.',
	POW_DEFAULT: 'Calling pow() without an explicit base is deprecated.',
});

export default emitDeprecation;

// yourLibCode.js
import emitDeprecation from './deprecations.js';

export function add (a, b, c) {
	if (c === undefined) {
		emitDeprecation('ADD_THREE'); //
	}
}

Background

This helper allows you to specify all your deprecation codes and messages in one place, getting out a function which you can use to emit deprecation warnings from your main code. It makes use of process.emitWarning and the special DeprecationWarning warning type, meaning users can use Node's --*-warnings and --*-deprecation CLI flags to control the behavior of your deprecation warnings. It also makes sure that no warning code is emitted more than once to follow documented best practices.

License

MIT © eritbh