internals

How jq recurse Works for Tree Traversal: Implementation Guide

April 11, 2026 jqlang/jq ↗

The jq recurse filter performs depth-first tree traversal by defining a self-referential helper function that yields the current node then recursively descends through user-specified children, implemented entirely in jq's own scripting language within src/builtin.jq.

The recurse filter is one of jq's most powerful built-ins for navigating nested JSON structures. Unlike many core functions implemented in C, recurse lives as a native jq definition in the jqlang/jq repository, demonstrating the language's ability to express complex recursive algorithms using closures and self

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