mongez-supportive-is-primitives

Primitive type checking in JavaScript requires precise predicates to handle edge cases like NaN, Infinity, and wrapper objects. This Skill provides deterministic O(1) checks using isString, isNumeric, isInt, isFloat, isPrimitive, and isScalar to validate inputs and narrow types.

Validating numeric strings against actual numbers in TypeScript is handled by the isNumeric predicate, which distinguishes between values like "123" and 123. The Skill documents these semantics thoroughly to help developers reason about type checks without relying on ad-hoc typeof checks.

To set up primitive type predicates, import isString, isNumeric, isInt, isFloat, isPrimitive, or isScalar directly from @mongez/supportive-is in your JavaScript or TypeScript project, then apply them to validate common values and narrow types across your codebase.

Yes, primitive type checking with these predicates works with both JavaScript and TypeScript projects. The Skill provides guidance for type narrowing and input validation across dynamic and statically-typed codebases, ensuring consistent semantics regardless of the environment.

Typeof returns unexpected results for wrapper objects because it identifies them as objects rather than primitives. Predicates like isPrimitive and isScalar bypass this by applying deterministic checks that account for wrapper objects, symbols, null, and undefined edge cases.

Ad-hoc typeof checks lack clear semantics for numeric strings, NaN, Infinity, and wrapper objects. Dedicated type predicates solve this by offering documented edge case handling and deterministic O(1) checks, preventing practical pitfalls when validating dynamic data.