is.js is a JavaScript validation library and data type checker. It provides a suite of utilities to verify whether variables are primitives, arrays, functions, or specific object types.
The project allows for the implementation of custom validation logic and the use of naming namespaces to override default rules and regular expressions.
It covers a broad range of validation capabilities, including numeric arithmetic properties, date and time analysis for relative and absolute ranges, and string format verification for patterns such as emails, URLs, and IP addresses. The library also includes environment detection utilities to identify browser versions, operating systems, and network connectivity status.
