Brand checking of React Elements.

Compressible Content-Type / mime checking

Type checking for JavaScript functions

Structural equality checking for JavaScript values

Isomorphic, functional type-checking for Javascript

Runtime type checking for React props and similar objects.

Precondition checking utilities.

Type checking and diagnostics for Astro projects

Build environment checking (a la autoconf) for node.js

complete type checking for node

Runtime type checking helpers

Tiny runtime type checking utils

Static checking for broken internal links

Type checking and DDD for JavaScript

TypeScript with some extras for type-checking.

Another biased type checking solution for Javascript

A spelling dictionary library useful for checking words and getting suggestions.

Dead-simple spell checking in CodeMirror.

Eslint plugin checking architecture boundaries between elements

Type checking from node core