Check that given value is any type of error and instanceof Error.

A ridiculously light-weight argument validator (now browser friendly)

This transformer wraps all typeof expressions with a method that replicates native behaviour. (ie. returning “symbol” for symbols)

Deprecated. Utilities for ES3, most of which have been adopted or superseded in ES5.1. Adapted from Douglas Crockford's Remedial JavaScript

Determine a value's type.

Type-safe implementation of invariant with positionals.

Get the native JavaScript type of a value, preceded by the appropriate indefinite article (either `a` or `an`), for use in error messages.

WASI threads proposal implementation in JavaScript

A set of JavaScript helper functions to check for types

Additional JSON-Schema keywords for Ajv JSON validator

maximally minimal type-testing library

TypeScript definitions for kdbush

is that thing a function? Use this module to find out

TypeScript definitions for json-bigint

Comprehensive collection of type guards for JavaScript and TypeScript; Inspired by Elixir

This transformer wraps all typeof expressions with a method that replicates native behaviour. (ie. returning “symbol” for symbols)

Check if a value is a function

Lazy assertions without performance penalty

Node module. typeOf('a string') == 'string', typeOf([]) == 'array', etc.. Also supports named functions detections aka javascript classes

Type checking for JavaScript functions