jfilter is a lightweight JavaScript/TypeScript library that compiles Splunk‑style query strings into reusable predicate functions for arbitrary objects. It lets developers write expressive filters (e.g., `log.level = warn and log.event in (core, transport)`) that are parsed into composable accessor + predicate functions, supporting nested properties, array/iterable matching, ranges, globs, regexes, relative times, and custom accessors. The tool is aimed at developers who need fast, declarative filtering of complex data structures without pulling in heavyweight validation libraries.