sindresorhus/type-fest

SnakeCaseProperties doesn't handle PascalCase and UPPERCASE

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#223 opened on Jun 26, 2021

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bugcomponent:casinghelp wanted

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Description

I have a type with PascalCase and a few uppercase properties, e.g.

Identifiers: {
    MarketplaceASIN: {
	MarketplaceId: string;
	ASIN: string;
    },
}

SnakeCasedPropertiesDeep turns this into:

_identifiers: {
    _marketplace_a_s_i_n: {
        _marketplace_id: string;
        _a_s_i_n: string;
    };
};

It doesn't handle the cases where the property starts with an uppercase and where the property contains multiple uppercase letters in a row.

I could overcome the first issue by using CamelCasedPropertiesDeep first.

What I would expect is:

identifiers: {
    marketplace_asin: {
        marketplace_id: string;
        asin: string;
    };
};

During runtime I use lodash's https://lodash.com/docs/4.17.15#snakeCase method. Is there a way to use the same method for the type?

Contributor guide

Research direction
Study the lodash snakeCase method to understand its algorithm, then implement a type level version using TypeScript template literal types that correctly handles sequences of uppercase letters (e.g., 'ASIN' > 'asin').
Tech stack
typescript
Domain
tooling
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
TypeScriptunderstanding of template literal types
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65