Is Packages

Isomorphic, functional type-checking for Javascript

Returns `true` if the string is upper case only.

Returns `true` if the string is lower case only

Determine if a filename and/or buffer is text or binary. Smarter detection than the other solutions.

Is this value an ES BigInt?

Check if a Buffer/Uint8Array is a PNG image

Is this value a JS WeakSet? This module works cross-realm/iframe, and despite ES6 @@toStringTag.

Is this value a JS WeakMap? This module works cross-realm/iframe, and despite ES6 @@toStringTag.

Returns true if the value passed is all whitespace.

Check if a Buffer/Uint8Array is a JPEG image

Returns true if a windows file path has invalid characters.

Check if a string is an IP address

Check whether a RegExp flag is supported

Function argument validation for humans

Is this a bluebird promise I see before me?

Check if a Buffer/Uint8Array is a GIF image

Check if a URL is relative

Returns true if the given number is odd, and is an integer that does not exceed the JavaScript MAXIMUM_SAFE_INTEGER.

Is the current JS environment a touch device?

Utilities to get and check variable types (isString, isPlainObject, isRegExp, etc)