@sindresorhus/is
Type check values
Type check values
Function argument validation for humans
Utilities to get and check variable types (isString, isPlainObject, isRegExp, etc)
A tiny javascript type testing tool
Enhances a JavaScript class by adding an is<Class> property to compare types between realms.
Create custom JavaScript errors that also match instanceof.
Minimal JavaScript type checking library
Check if the given value is of the particular type or types.
Define errors without frills, but with stack traces and instanceof support.
Safely and simply extend native Error with prototype chaining support
Additional ESLint rules.
Lightweight library for determining types of variables based on battle-tested implementation from lodash but having a fraction of overall size.
Better 'typeof'. Detects real type of the objects like 'Array()', 'new Number(1)', 'new Boolean(true)', etc.
Additional ESLint rules.
Validate the type of object's properties.
Type check values: `is.string('🦄') //=> true`
Like instanceof, but uses class name strings.
SlimIO is (JavaScript Primitives & Objects type checker)
Check if a value is an error constructor
Workaround for subclassing errors. Both instanceof and stack are functional.